The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

cyrus-imapd recognized commands before switching to an encrypted channel via STARTTLS. Attackers could potentially exploit that to inject plain text commands (CVE-2011-1926).

From Red Hat Security Advisory 2011:0859 :

Updated cyrus-imapd packages that fix one security issue are now available for Red Hat Enterprise Linux 4, 5, and 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The cyrus-imapd packages contain a high-performance mail server with IMAP, POP3, NNTP, and Sieve support.

It was discovered that cyrus-imapd did not flush the received commands buffer after switching to TLS encryption for IMAP, LMTP, NNTP, and POP3 sessions. A man-in-the-middle attacker could use this flaw to inject protocol commands into a victim's TLS session initialization messages. This could lead to those commands being processed by cyrus-imapd, potentially allowing the attacker to steal the victim's mail or authentication credentials. (CVE-2011-1926)

Users of cyrus-imapd are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. After installing the update, cyrus-imapd will be restarted automatically.

The cyrus-imapd packages contain a high-performance mail server with IMAP, POP3, NNTP, and Sieve support.

It was discovered that cyrus-imapd did not flush the received commands buffer after switching to TLS encryption for IMAP, LMTP, NNTP, and POP3 sessions. A man-in-the-middle attacker could use this flaw to inject protocol commands into a victim's TLS session initialization messages. This could lead to those commands being processed by cyrus-imapd, potentially allowing the attacker to steal the victim's mail or authentication credentials. (CVE-2011-1926)

Users of cyrus-imapd are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. After installing the update, cyrus-imapd will be restarted automatically.

Cyrus-imapd recognized commands before switching to an encrypted channel via STARTTLS. Attackers could potentially exploit that to inject plain text commands. (CVE-2011-1926)

cyrus-imapd recognized commands before switching to an encrypted channel via STARTTLS. Attackers could potentially exploit that to inject plain text commands. (CVE-2011-1926)

It was discovered that the STARTTLS implementation of the Kolab Cyrus IMAP server does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted IMAP, LMTP, NNTP and POP3 sessions by sending a cleartext command that is processed after TLS is in place.

- Tue May 17 2011 Michal Hlavinka <mhlavink at redhat.com>
    - 2.3.16-8

    - fix CVE-2011-1926: STARTTLS plaintext command       injection vulnerability

    - Fri Jan 21 2011 Michal Hlavinka <mhlavink at       redhat.com> - 2.3.16-7

    - don't force sync io for all filesystems

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.

- Wed May 18 2011 Michal Hlavinka <mhlavink at redhat.com>
    - 2.3.16-5

    - fix CVE-2011-1926: STARTTLS plaintext command       injection vulnerability

    - Fri Jan 21 2011 Michal Hlavinka <mhlavink at       redhat.com> - 2.3.16-4

    - don't force sync io for all filesystems

    - Tue Apr 20 2010 Michal Hlavinka <mhlavink at       redhat.com> - 2.3.16-3

    - add support for QoS marked traffic (#576652)

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.

It was discovered that the STARTTLS implementation of the Cyrus IMAP server does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted IMAP, LMTP, NNTP and POP3 sessions by sending a cleartext command that is processed after TLS is in place.

Updated cyrus-imapd packages that fix one security issue are now available for Red Hat Enterprise Linux 4, 5, and 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The cyrus-imapd packages contain a high-performance mail server with IMAP, POP3, NNTP, and Sieve support.

It was discovered that cyrus-imapd did not flush the received commands buffer after switching to TLS encryption for IMAP, LMTP, NNTP, and POP3 sessions. A man-in-the-middle attacker could use this flaw to inject protocol commands into a victim's TLS session initialization messages. This could lead to those commands being processed by cyrus-imapd, potentially allowing the attacker to steal the victim's mail or authentication credentials. (CVE-2011-1926)

Users of cyrus-imapd are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. After installing the update, cyrus-imapd will be restarted automatically.

A vulnerability has been identified and fixed in cyrus-imapd :

The STARTTLS implementation in Cyrus IMAP Server before 2.4.7 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted sessions by sending a cleartext command that is processed after TLS is in place, related to a plaintext command injection attack, a similar issue to CVE-2011-0411 (CVE-2011-1926).

Packages for 2009.0 are provided as of the Extended Maintenance Program. Please visit this link to learn more:
http://store.mandriva.com/product_info.php?cPath=149 products_id=490

The updated packages have been patched to correct this issue.

The remote IMAP service contains a software flaw in its STARTTLS implementation that could allow a remote, unauthenticated attacker to inject commands during the plaintext protocol phase that will be executed during the ciphertext protocol phase. 

Successful exploitation could allow an attacker to steal a victim's email or associated SASL (Simple Authentication and Security Layer) credentials.

ID	Name	Product	Family	Severity
75809	openSUSE Security Update : cyrus-imapd (openSUSE-SU-2011:0800-1)	Nessus	SuSE Local Security Checks	medium
75457	openSUSE Security Update : cyrus-imapd (openSUSE-SU-2011:0800-1)	Nessus	SuSE Local Security Checks	medium
68289	Oracle Linux 4 / 5 / 6 : cyrus-imapd (ELSA-2011-0859)	Nessus	Oracle Linux Local Security Checks	medium
61063	Scientific Linux Security Update : cyrus-imapd on SL4.x, SL5.x, SL6.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	medium
57174	SuSE 10 Security Update : cyrus-imapd (ZYPP Patch Number 7583)	Nessus	SuSE Local Security Checks	medium
55621	SuSE 10 Security Update : cyrus-imapd (ZYPP Patch Number 7584)	Nessus	SuSE Local Security Checks	medium
55618	SuSE 11.1 Security Update : cyrus-imapd (SAT Patch Number 4731)	Nessus	SuSE Local Security Checks	medium
55617	SuSE9 Security Update : cyrus-imapd (YOU Patch Number 12776)	Nessus	SuSE Local Security Checks	medium
55065	Debian DSA-2258-1 : kolab-cyrus-imapd - implementation error	Nessus	Debian Local Security Checks	medium
55052	Fedora 14 : cyrus-imapd-2.3.16-8.fc14 (2011-7217)	Nessus	Fedora Local Security Checks	medium
55051	Fedora 13 : cyrus-imapd-2.3.16-5.fc13 (2011-7193)	Nessus	Fedora Local Security Checks	medium
55030	Debian DSA-2242-1 : cyrus-imapd-2.2 - implementation error	Nessus	Debian Local Security Checks	medium
55013	RHEL 4 / 5 / 6 : cyrus-imapd (RHSA-2011:0859)	Nessus	Red Hat Local Security Checks	medium
55000	CentOS 4 / 5 : cyrus-imapd (CESA-2011:0859)	Nessus	CentOS Local Security Checks	medium
54639	Mandriva Linux Security Advisory : cyrus-imapd (MDVSA-2011:100)	Nessus	Mandriva Local Security Checks	medium
52609	IMAP Service STARTTLS Plaintext Command Injection	Nessus	Misc.	medium

Detections

Analytics

CVE-2011-1926

critical

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium