serve_notify in CVS 1.12.x through 1.12.8, and 1.11.x through 1.11.16, does not properly handle empty data lines, which may allow remote attackers to perform an "out-of-bounds" write for a single byte to execute arbitrary code or modify critical program data.

A number of vulnerabilities were discovered in CVS by Stefan Esser, Sebastian Krahmer, and Derek Price.

- Insufficient input validation while processing 'Entry' lines.
(CVE-2004-0414)

- A double-free resulting from erroneous state handling while processing 'Argumentx' commands. (CVE-2004-0416)

- Integer overflow while processing 'Max-dotdot' commands.
(CVE-2004-0417)

- Erroneous handling of empty entries handled while processing 'Notify' commands. (CVE-2004-0418)

- A format string bug while processing CVS wrappers.

- Single-byte buffer underflows while processing configuration files from CVSROOT.

- Various other integer overflows.

Additionally, iDEFENSE reports an undocumented command-line flag used in debugging does not perform input validation on the given path names.

CVS servers ('cvs server' or :pserver: modes) are affected by these vulnerabilities. They vary in impact but include information disclosure (the iDEFENSE-reported bug), denial-of-service (CVE-2004-0414, CVE-2004-0416, CVE-2004-0417 and other bugs), or possibly arbitrary code execution (CVE-2004-0418). In very special situations where the attacker may somehow influence the contents of CVS configuration files in CVSROOT, additional attacks may be possible.

New cvs packages that have been upgraded to cvs-1.11.17 are available for Slackware 8.1, 9.0, 9.1, and -current to fix various security issues. Sites running a CVS server should upgrade to the new CVS package right away.

Sebastian Krahmer and Stefan Esser discovered several vulnerabilities in the CVS server, which serves the popular Concurrent Versions System. The Common Vulnerabilities and Exposures project identifies the following problems :

  - CAN-2004-0416: double-free() in error_prog_name
  - CAN-2004-0417: argument integer overflow

  - CAN-2004-0418: out of bound writes in serve_notify()

Derek Robert Price discovered a potential buffer overflow vulnerability in the CVS server, based on a malformed Entry, which serves the popular Concurrent Versions System.

The remote host is affected by the vulnerability described in GLSA-200406-06 (CVS: additional DoS and arbitrary code execution vulnerabilities)

    A team audit of the CVS source code performed by Stefan Esser and Sebastian     Krahmer resulted in the discovery of several remotely exploitable     vulnerabilities including:
    no-null-termination of 'Entry' lines     error_prog_name 'double-free()'     Argument integer overflow     serve_notify() out of bounds writes   Impact :

    An attacker could use these vulnerabilities to cause a Denial of Service or     execute arbitrary code with the permissions of the user running cvs.
  Workaround :

    There is no known workaround at this time. All users are advised to upgrade     to the latest available version of CVS.

Another vulnerability was discovered related to 'Entry' lines in cvs, by the development team (CVE-2004-0414).

As well, Stefan Esser and Sebastian Krahmer performed an audit on the cvs source code and discovered a number of other problems, including :

A double-free condition in the server code is exploitable (CVE-2004-0416).

By sending a large number of arguments to the CVS server, it is possible to cause it to allocate a huge amount of memory which does not fit into the address space, causing an error (CVE-2004-0417).

It was found that the serve_notify() function would write data out of bounds (CVE-2004-0418).

The provided packages update cvs to 1.11.16 and include patches to correct all of these problems.

The remote host is missing the patch for the advisory SuSE-SA:2004:015 (cvs).


The Concurrent Versions System (CVS) offers tools which allow developers to share and maintain large software projects.
Various remotely exploitable conditions have been found during a source code review of CVS done by Stefan Esser and Sebastian Krahmer (SuSE Security-Team).
These bugs allow remote attackers to execute arbitrary code as the user the CVS server runs as. Since there is no easy workaround we strongly recommend to update the cvs package.
The update packages fix vulnerabilities which have been assigned the CAN numbers CVE-2004-0416, CVE-2004-0417 and CVE-2004-0418.
The cvs packages shipped by SUSE (as well as our recent updates for CVS) are not vulnerable to CVE-2004-0414.

Please download the update package for your distribution and verify its integrity by the methods listed in section 3) of this announcement.
Then, install the package using the command 'rpm -Fhv file.rpm' to apply the update.

An updated cvs package that fixes several server vulnerabilities, which could be exploited by a malicious client, is now available.

CVS is a version control system frequently used to manage source code repositories.

While investigating a previously fixed vulnerability, Derek Price discovered a flaw relating to malformed 'Entry' lines which lead to a missing NULL terminator. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the name CVE-2004-0414 to this issue.

Stefan Esser and Sebastian Krahmer conducted an audit of CVS and fixed a number of issues that may have had security consequences.

Among the issues deemed likely to be exploitable were :

-- a double-free relating to the error_prog_name string (CVE-2004-0416) -- an argument integer overflow (CVE-2004-0417) -- out-of-bounds writes in serv_notify (CVE-2004-0418).

An attacker who has access to a CVS server may be able to execute arbitrary code under the UID on which the CVS server is executing.

Users of CVS are advised to upgrade to this updated package, which contains backported patches correcting these issues.

Red Hat would like to thank Stefan Esser, Sebastian Krahmer, and Derek Price for auditing, disclosing, and providing patches for these issues.

The remote CVS server, according to its version number, might allow an attacker to execute arbitrary commands on the remote system because of a flaw relating to malformed Entry lines which lead to a missing NULL terminator. 

Among the issues deemed likely to be exploitable were:

  - A double-free relating to the error_prog_name string.     (CVE-2004-0416)

  - An argument integer overflow. (CVE-2004-0417)

  - Out-of-bounds writes in serv_notify. (CVE-2004-0418)

ID	Name	Product	Family	Severity
37427	FreeBSD : cvs -- numerous vulnerabilities (d2102505-f03d-11d8-81b0-000347a4fa7d)	Nessus	FreeBSD Local Security Checks	critical
18779	Slackware 8.1 / 9.0 / 9.1 / current : cvs (SSA:2004-161-01)	Nessus	Slackware Local Security Checks	critical
15356	Debian DSA-519-1 : cvs - several vulnerabilities	Nessus	Debian Local Security Checks	critical
15354	Debian DSA-517-1 : cvs - buffer overflow	Nessus	Debian Local Security Checks	critical
14517	GLSA-200406-06 : CVS: additional DoS and arbitrary code execution vulnerabilities	Nessus	Gentoo Local Security Checks	critical
14157	Mandrake Linux Security Advisory : cvs (MDKSA-2004:058)	Nessus	Mandriva Local Security Checks	critical
13831	SuSE-SA:2004:015: cvs	Nessus	SuSE Local Security Checks	critical
12500	RHEL 2.1 / 3 : cvs (RHSA-2004:233)	Nessus	Red Hat Local Security Checks	critical
12265	CVS < 1.11.17 / 1.12.9 Multiple Vulnerabilities	Nessus	Misc.	high

Detections

Analytics

CVE-2004-0418

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Tenable Plugins

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