Integer overflow in the MallocFrameBuffer function in vncviewer.c in LibVNCServer 0.9.9 and earlier allows remote VNC servers to cause a denial of service (crash) and possibly execute arbitrary code via an advertisement for a large screen size, which triggers a heap-based buffer overflow.

The remote Ubuntu 16.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-4587-1 advisory.

    Nicolas Ruff discovered that iTALC had buffer overflows, divide-by-zero errors and didn't check malloc     return values. A remote attacker could use these issues to cause a denial of service or possibly execute     arbitrary code. (CVE-2014-6051, CVE-2014-6052, CVE-2014-6053, CVE-2014-6054, CVE-2014-6055)

    Josef Gajdusek discovered that iTALC had heap-based buffer overflow vulnerabilities. A remote attacker     could used these issues to cause a denial of service or possibly execute arbitrary code. (CVE-2016-9941,     CVE-2016-9942)

    It was discovered that iTALC had an out-of-bounds write, multiple heap out-of-bounds writes, an infinite     loop, improper initializations, and null pointer vulnerabilities. A remote attacker could used these     issues to cause a denial of service or possibly execute arbitrary code. (CVE-2018-15127, CVE-2018-20019,     CVE-2018-20020, CVE-2018-20021, CVE-2018-20022, CVE-2018-20023, CVE-2018-20024, CVE-2018-20748,     CVE-2018-20749, CVE-2018-20750, CVE-2018-7225, CVE-2019-15681)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Several vulnerabilities have been identified in the VNC code of iTALC, a classroom management software. All vulnerabilities referenced below are issues that have originally been reported against Debian source package libvncserver. The italc source package in Debian ships a custom-patched version of libvncserver, thus libvncserver's security fixes required porting over.

CVE-2014-6051

Integer overflow in the MallocFrameBuffer function in vncviewer.c in LibVNCServer allowed remote VNC servers to cause a denial of service (crash) and possibly executed arbitrary code via an advertisement for a large screen size, which triggered a heap-based buffer overflow.

CVE-2014-6052

The HandleRFBServerMessage function in libvncclient/rfbproto.c in LibVNCServer did not check certain malloc return values, which allowed remote VNC servers to cause a denial of service (application crash) or possibly execute arbitrary code by specifying a large screen size in a (1) FramebufferUpdate, (2) ResizeFrameBuffer, or (3) PalmVNCReSizeFrameBuffer message.

CVE-2014-6053

The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer did not properly handle attempts to send a large amount of ClientCutText data, which allowed remote attackers to cause a denial of service (memory consumption or daemon crash) via a crafted message that was processed by using a single unchecked malloc.

CVE-2014-6054

The rfbProcessClientNormalMessage function in libvncserver/rfbserver.c in LibVNCServer allowed remote attackers to cause a denial of service (divide-by-zero error and server crash) via a zero value in the scaling factor in a (1) PalmVNCSetScaleFactor or (2) SetScale message.

CVE-2014-6055

Multiple stack-based buffer overflows in the File Transfer feature in rfbserver.c in LibVNCServer allowed remote authenticated users to cause a denial of service (crash) and possibly execute arbitrary code via a (1) long file or (2) directory name or the (3) FileTime attribute in a rfbFileTransferOffer message.

CVE-2016-9941

Heap-based buffer overflow in rfbproto.c in LibVNCClient in LibVNCServer allowed remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message containing a subrectangle outside of the client drawing area.

CVE-2016-9942

Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer allowed remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeded what is specified by the tile dimensions.

CVE-2018-6307

LibVNC contained heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.

CVE-2018-7225

An issue was discovered in LibVNCServer.
rfbProcessClientNormalMessage() in rfbserver.c did not sanitize msg.cct.length, leading to access to uninitialized and potentially sensitive data or possibly unspecified other impact (e.g., an integer overflow) via specially crafted VNC packets.

CVE-2018-15126

LibVNC contained heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.

CVE-2018-15127

LibVNC contained heap out-of-bound write vulnerability in server code of file transfer extension that can result remote code execution

CVE-2018-20749

LibVNC contained a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

CVE-2018-20750

LibVNC contained a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

CVE-2018-20019

LibVNC contained multiple heap out-of-bound write vulnerabilities in VNC client code that can result remote code execution

CVE-2018-20748

LibVNC contained multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete.

CVE-2018-20020

LibVNC contained heap out-of-bound write vulnerability inside structure in VNC client code that can result remote code execution

CVE-2018-20021

LibVNC contained a CWE-835: Infinite loop vulnerability in VNC client code. Vulnerability allows attacker to consume excessive amount of resources like CPU and RAM

CVE-2018-20022

LibVNC contained multiple weaknesses CWE-665: Improper Initialization vulnerability in VNC client code that allowed attackers to read stack memory and could be abused for information disclosure. Combined with another vulnerability, it could be used to leak stack memory layout and in bypassing ASLR.

CVE-2018-20023

LibVNC contained CWE-665: Improper Initialization vulnerability in VNC Repeater client code that allowed attacker to read stack memory and could be abused for information disclosure. Combined with another vulnerability, it could be used to leak stack memory layout and in bypassing ASLR.

CVE-2018-20024

LibVNC contained NULL pointer dereference in VNC client code that could result DoS.

CVE-2019-15681

LibVNC contained a memory leak (CWE-655) in VNC server code, which allowed an attacker to read stack memory and could be abused for information disclosure. Combined with another vulnerability, it could be used to leak stack memory and bypass ASLR. This attack appeared to be exploitable via network connectivity.

For Debian 8 'Jessie', these problems have been fixed in version 1:2.0.2+dfsg1-2+deb8u1.

We recommend that you upgrade your italc packages.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host is affected by the vulnerability described in GLSA-201612-36 (TigerVNC: Integer overflow)

    TigerVNC is impacted by the same vulnerability as found in       CVE-2014-6051. An integer overflow, leading to a heap-based buffer       overflow, was found in the way screen sizes were handled.
  Impact :

    A remote attacker, utilizing a malicious VNC server, could execute       arbitrary code with the privileges of the user running the client, or       cause a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

Nicolas Ruff reports :

Integer overflow in MallocFrameBuffer() on client side.

Lack of malloc() return value checking on client side.

Server crash on a very large ClientCutText message.

Server crash when scaling factor is set to zero.

Multiple stack overflows in File Transfer feature.

The LibVNCServer package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

  - bsc#854151: Restrict the SSL cipher suite.

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The LibVNCServer package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

  - bsc#854151: Restrict the SSL cipher suite.

The libvncserver package was updated to fix the following security issues :

  - bsc#897031: fix several security issues :

  - CVE-2014-6051: Integer overflow in MallocFrameBuffer()     on client side.

  - CVE-2014-6052: Lack of malloc() return value checking on     client side.

  - CVE-2014-6053: Server crash on a very large     ClientCutText message.

  - CVE-2014-6054: Server crash when scaling factor is set     to zero.

  - CVE-2014-6055: Multiple stack overflows in File Transfer     feature.

Note that Tenable Network Security has extracted the preceding description block directly from the SUSE security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host is affected by the vulnerability described in GLSA-201507-07 (LibVNCServer: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in LibVNCServer. Please       review the CVE identifiers referenced below for details.
  Impact :

    A remote attacker may be able to execute arbitrary code with the       privileges of the process or cause a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

Several vulnerabilities have been discovered in libvncserver, a library to implement VNC server functionality. These vulnerabilities might result in the execution of arbitrary code or denial of service in both the client and the server side.

For the oldstable distribution (squeeze), these problems have been fixed in version 0.9.7-2+deb6u1.

This update has been prepared by Nguyen Cong.

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Updated libvncserver packages fix security vulnerabilities :

An integer overflow in liblzo before 2.07 allows attackers to cause a denial of service or possibly code execution in applications using performing LZO decompression on a compressed payload from the attacker (CVE-2014-4607).

The libvncserver library is built with a bundled copy of minilzo, which is a part of liblzo containing the vulnerable code.

A malicious VNC server can trigger incorrect memory management handling by advertising a large screen size parameter to the VNC client. This would result in multiple memory corruptions and could allow remote code execution on the VNC client (CVE-2014-6051, CVE-2014-6052).

A malicious VNC client can trigger multiple DoS conditions on the VNC server by advertising a large screen size, ClientCutText message length and/or a zero scaling factor parameter (CVE-2014-6053, CVE-2014-6054).

A malicious VNC client can trigger multiple stack-based buffer overflows by passing a long file and directory names and/or attributes (FileTime) when using the file transfer message feature (CVE-2014-6055).

Updated libvncserver packages that fix two security issues are now available for Red Hat Enterprise Linux 6.5 Extended Update Support.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

LibVNCServer is a library that allows for easy creation of VNC server or client functionality.

An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way screen sizes were handled by LibVNCServer. A malicious VNC server could use this flaw to cause a client to crash or, potentially, execute arbitrary code in the client. (CVE-2014-6051)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

Red Hat would like to thank oCERT for reporting these issues. oCERT acknowledges Nicolas Ruff as the original reporter.

All libvncserver users are advised to upgrade to these updated packages, which contain backported patches to correct these issues.
All running applications linked against libvncserver must be restarted for this update to take effect.

Several vulnerabilities have been discovered in libvncserver, a library to implement VNC server functionality. These vulnerabilities might result in the execution of arbitrary code or denial of service in both the client and the server side.

Updated libvncserver packages fix security vulnerabilities :

A malicious VNC server can trigger incorrect memory management handling by advertising a large screen size parameter to the VNC client. This would result in multiple memory corruptions and could allow remote code execution on the VNC client (CVE-2014-6051, CVE-2014-6052).

A malicious VNC client can trigger multiple DoS conditions on the VNC server by advertising a large screen size, ClientCutText message length and/or a zero scaling factor parameter (CVE-2014-6053, CVE-2014-6054).

A malicious VNC client can trigger multiple stack-based buffer overflows by passing a long file and directory names and/or attributes (FileTime) when using the file transfer message feature (CVE-2014-6055).

Additionally libvncserver has been built against the new system minilzo library which is also being provided with this advisory.

An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way screen sizes were handled by LibVNCServer. A malicious VNC server could use this flaw to cause a client to crash or, potentially, execute arbitrary code in the client. (CVE-2014-6051)

A NULL pointer dereference flaw was found in LibVNCServer's framebuffer setup. A malicious VNC server could use this flaw to cause a VNC client to crash. (CVE-2014-6052)

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)

A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to '0'. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6054)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

All running applications linked against libvncserver must be restarted for this update to take effect.

Updated libvncserver packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6 and 7.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

LibVNCServer is a library that allows for easy creation of VNC server or client functionality.

An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way screen sizes were handled by LibVNCServer. A malicious VNC server could use this flaw to cause a client to crash or, potentially, execute arbitrary code in the client. (CVE-2014-6051)

A NULL pointer dereference flaw was found in LibVNCServer's framebuffer setup. A malicious VNC server could use this flaw to cause a VNC client to crash. (CVE-2014-6052)

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)

A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to '0'. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6054)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

Red Hat would like to thank oCERT for reporting these issues. oCERT acknowledges Nicolas Ruff as the original reporter.

All libvncserver users are advised to upgrade to these updated packages, which contain backported patches to correct these issues.
All running applications linked against libvncserver must be restarted for this update to take effect.

From Red Hat Security Advisory 2014:1826 :

Updated libvncserver packages that fix multiple security issues are now available for Red Hat Enterprise Linux 6 and 7.

Red Hat Product Security has rated this update as having Moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

LibVNCServer is a library that allows for easy creation of VNC server or client functionality.

An integer overflow flaw, leading to a heap-based buffer overflow, was found in the way screen sizes were handled by LibVNCServer. A malicious VNC server could use this flaw to cause a client to crash or, potentially, execute arbitrary code in the client. (CVE-2014-6051)

A NULL pointer dereference flaw was found in LibVNCServer's framebuffer setup. A malicious VNC server could use this flaw to cause a VNC client to crash. (CVE-2014-6052)

A NULL pointer dereference flaw was found in the way LibVNCServer handled certain ClientCutText message. A remote attacker could use this flaw to crash the VNC server by sending a specially crafted ClientCutText message from a VNC client. (CVE-2014-6053)

A divide-by-zero flaw was found in the way LibVNCServer handled the scaling factor when it was set to '0'. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6054)

Two stack-based buffer overflow flaws were found in the way LibVNCServer handled file transfers. A remote attacker could use this flaw to crash the VNC server using a malicious VNC client.
(CVE-2014-6055)

Red Hat would like to thank oCERT for reporting these issues. oCERT acknowledges Nicolas Ruff as the original reporter.

All libvncserver users are advised to upgrade to these updated packages, which contain backported patches to correct these issues.
All running applications linked against libvncserver must be restarted for this update to take effect.

security fix, unbundles libvncserver and uses the system libvncserver.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Various security fixes, including CVE-2014-6051, CVE-2014-6052, CVE-2014-6053, CVE-2014-6054, CVE-2014-6055

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote Ubuntu 14.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-2365-1 advisory.

    Nicolas Ruff discovered that LibVNCServer incorrectly handled memory when being advertised large screen     sizes by the server. If a user were tricked into connecting to a malicious server, an attacker could use     this issue to cause a denial of service, or possibly execute arbitrary code. (CVE-2014-6051,     CVE-2014-6052)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled large ClientCutText messages. A remote     attacker could use this issue to cause a server to crash, resulting in a denial of service.
    (CVE-2014-6053)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled zero scaling factor values. A remote     attacker could use this issue to cause a server to crash, resulting in a denial of service.
    (CVE-2014-6054)

    Nicolas Ruff discovered that LibVNCServer incorrectly handled memory in the file transfer feature. A     remote attacker could use this issue to cause a server to crash, resulting in a denial of service, or     possibly execute arbitrary code. (CVE-2014-6055)

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
141545	Ubuntu 16.04 LTS : iTALC vulnerabilities (USN-4587-1)	Nessus	Ubuntu Local Security Checks	critical
130408	Debian DLA-1979-1 : italc security update	Nessus	Debian Local Security Checks	critical
95739	GLSA-201612-36 : TigerVNC: Integer overflow	Nessus	Gentoo Local Security Checks	high
93990	FreeBSD : libvncserver -- multiple security vulnerabilities (cb3f036d-8c7f-11e6-924a-60a44ce6887b)	Nessus	FreeBSD Local Security Checks	high
87721	SUSE SLES12 Security Update : LibVNCServer (SUSE-SU-2015:2088-2)	Nessus	SuSE Local Security Checks	high
87389	openSUSE Security Update : LibVNCServer (openSUSE-2015-851)	Nessus	SuSE Local Security Checks	high
87105	SUSE SLED11 / SLES11 Security Update : LibVNCServer (SUSE-SU-2015:2110-1)	Nessus	SuSE Local Security Checks	high
87064	SUSE SLED12 / SLES12 Security Update : LibVNCServer (SUSE-SU-2015:2088-1)	Nessus	SuSE Local Security Checks	high
84606	GLSA-201507-07 : LibVNCServer: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
82784	Debian DLA-197-1 : libvncserver security update	Nessus	Debian Local Security Checks	high
82399	Mandriva Linux Security Advisory : libvncserver (MDVSA-2015:146)	Nessus	Mandriva Local Security Checks	high
81143	RHEL 6 : libvncserver (RHSA-2015:0113)	Nessus	Red Hat Local Security Checks	high
79629	Debian DSA-3081-1 : libvncserver - security update	Nessus	Debian Local Security Checks	high
79589	Mandriva Linux Security Advisory : libvncserver (MDVSA-2014:229)	Nessus	Mandriva Local Security Checks	high
79230	Scientific Linux Security Update : libvncserver on SL6.x, SL7.x i386/x86_64 (20141111)	Nessus	Scientific Linux Local Security Checks	high
79202	RHEL 6 / 7 : libvncserver (RHSA-2014:1826)	Nessus	Red Hat Local Security Checks	high
79199	Oracle Linux 6 / 7 : libvncserver (ELSA-2014-1826)	Nessus	Oracle Linux Local Security Checks	high
79188	CentOS 6 / 7 : libvncserver (CESA-2014:1826)	Nessus	CentOS Local Security Checks	high
78095	Fedora 19 : krfb-4.11.5-4.fc19 (2014-11464)	Nessus	Fedora Local Security Checks	high
78053	Fedora 19 : libvncserver-0.9.10-0.6.20140718git9453be42.fc19 (2014-11541)	Nessus	Fedora Local Security Checks	high
78000	Fedora 21 : libvncserver-0.9.10-0.6.20140718git9453be42.fc21 (2014-11685)	Nessus	Fedora Local Security Checks	high
77982	Ubuntu 14.04 LTS : LibVNCServer vulnerabilities (USN-2365-1)	Nessus	Ubuntu Local Security Checks	critical
77942	Fedora 20 : libvncserver-0.9.10-0.6.20140718git9453be42.fc20 (2014-11537)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2014-6051

critical

Tenable Plugins

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