Core Security Technologies reported that previous upstream fixes addressing insufficient input validation flaw in pidgin / libpurple in function msnslplinkprocessmsg() are inefficient and can be bypassed. This flaw allows an attacker to overwrite pidgin's memory and possibly execute arbitrary code with the privileges of the user running application using libpurple.

This issue was previously tracked as CVE-2008-2927 (bug #453764) and CVE-2009-1376 (bug #500493, incomplete fix).

An out-of-bounds write flaw was found in the way Pidgin before 2.12.0 processed XML content. A malicious remote server could potentially use this flaw to crash Pidgin or execute arbitrary code in the context of the pidgin process.

Pidgin version <2.11.0 contains a vulnerability in X.509 Certificates imports specifically due to improper check of return values from gnutlsx509crtinit() and gnutlsx509crtimport() that can result in code execution. This attack appear to be exploitable via custom X.509 certificate from another client. This vulnerability appears to have been fixed in 2.11.0.

gtkutils.c in Pidgin before 2.10.0 on Windows allows user-assisted remote attackers to execute arbitrary programs via a file: URL in a message.

A heap overflow flaw was found in a regular expression parser in the NSS library used to match common names in certificates. A malicious site could present a carefully crafted certificate in such a way as to trigger the heap overflow leading to a crash or possibly execute arbitrary code as the user running a browser such as firefox.

The overflow happens when the browser checks if the hostname of the site you are visiting matches the Common Name (CN) field of the presented certificate. This check (certTestHostName) only happens automatically if the certificate is one that is signed by a Certificate Authority you have previously trusted. If the attacker presents a malicious self-signed certificate, or one signed by an untrusted CA, the user is presented with a dialog box about the certificate before the vulnerable function is called. If the user chooses to accept the certificate then the vulnerable function is called and the heap overflow happens. So this issue does require slightly more user interaction to be exploited.

Co-incidentally, the handling of regular expressions for NSS versions 3.12.3 and above was changed to use a different and simpler regular expression routine which is not vulnerable to this issue. Therefore where a system has NSS 3.12.3 installed, it is not vulnerable to this issue by default. (Although it is possible to change Firefox back to use the old vulnerable library it is not something that is expected users to have done, and is not an obvious documented ability)

For Red Hat Enterprise Linux 5, Firefox uses the system provided NSS library. This library was updated to a versions greater than 3.12.3 by RHBA-2009:1161 on 20th July 2009. Therefore systems updated to RHBA-2009:1161 are protected by default from this issue.

For Red Hat Enterprise Linux 4, Firefox uses the system provided NSS library. This library is due to be updated to a version greater than 3.12.3 and this will probably happen within the week (so before the embargo lifts).

For Red Hat Enterprise Linux 3 we do not ship Firefox but instead SeaMonkey which provides the NSS library. SeaMonkey will need updating to correct this issue.

Multiple integer overflows in the msnslplinkprocessmsg functions in the MSN protocol handler in (1) libpurple/protocols/msn/slplink.c and (2) libpurple/protocols/msnp9/slplink.c in Pidgin (formerly Gaim) before 2.5.6 on 32-bit platforms allow remote attackers to execute arbitrary code via a malformed SLP message with a crafted offset value, leading to buffer overflows. NOTE: this issue exists because of an incomplete fix for CVE-2008-2927.

A buffer overflow vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent from the server could potentially result in arbitrary code execution. A malicious server or an attacker who intercepts the network traffic can send an invalid size for a packet which will trigger a buffer overflow.

An out-of-bounds write vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could cause memory corruption resulting in code execution.

An exploitable memory corruption vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT MultiMX message sent via the server can result in an out-of-bounds write leading to memory disclosure and code execution.

Multiple memory corruption vulnerabilities exist in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could result in multiple buffer overflows, potentially resulting in code execution or memory disclosure.

A buffer overflow vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent by the server could potentially result in an out-of-bounds write of one byte. A malicious server can send a negative content-length in response to a HTTP request triggering the vulnerability.

A buffer overflow vulnerability exists in the handling of the MXIT protocol Pidgin. Specially crafted data sent via the server could potentially result in a buffer overflow, potentially resulting in memory corruption. A malicious server or an unfiltered malicious user can send negative length values to trigger this vulnerability.

Format string vulnerability in the logmessagecb function in otr-plugin.c in the Off-the-Record Messaging (OTR) pidgin-otr plugin before 3.2.1 for Pidgin might allow remote attackers to execute arbitrary code via format string specifiers in data that generates a log message.

Directory traversal vulnerability in slp.c in the MSN protocol plugin in libpurple in Pidgin 2.6.4 and Adium 1.3.8 allows remote attackers to read arbitrary files via a .. (dot dot) in an application/x-msnmsgrp2p MSN emoticon (aka custom smiley) request, a related issue to CVE-2004-0122. NOTE: it could be argued that this is resultant from a vulnerability in which an emoticon download request is processed even without a preceding text/x-mms-emoticon message that announced availability of the emoticon.

A buffer overflow flaw was found in the way Pidgin initiates file transfers. If a Pidgin client initiates a file transfer, and the remote target sends a malformed response, it triggers a buffer overflow.

The integer overflow fix for CVE-2008-2927 was incomplete on 32 bit platforms. If a Pidgin user can receive a specially crafted MSN message, it may be possible to execute arbitrary code with the permissions of the user running Pidgin.

This flaw is only exploitable by individuals who can message a user, which is controlled by the Pidgin privacy setting. The default setting is to only allow messages from users in the buddy list.

Buffer overflow in http.c in the MXit protocol plugin in libpurple in Pidgin before 2.10.7 allows remote servers to execute arbitrary code via a long HTTP header.

The NSS plugin in libpurple in Pidgin 2.4.3 does not verify SSL certificates, which makes it easier for remote attackers to trick a user into accepting an invalid server certificate for a spoofed service.

An integer overflow in Pidgin's MSN protocol handler could allow malformed SLP message to cause an integer overflow, which could result in arbitrary code execution.

This flaw is only exploitable by individuals who can message a user, which is controlled by the Pidgin privacy setting. The default setting is to only allow messages from users in the buddy list.

Absolute path traversal vulnerability in the untarblock function in win32/untar.c in Pidgin before 2.10.10 on Windows allows remote attackers to write to arbitrary files via a drive name in a tar archive of a smiley theme.

It was reported that the SSL/TLS plug-ins failed to check that the Basic Constraints extension allowed intermediate certificates to act as Certificate Authorities (CAs). An attacker could use this flaw to create a fake certificate that Pidgin would trust, which could be used for man-in-the-middle attacks.

This is the same situation as described in http://www.thoughtcrime.org/ie-ssl-chain.txt

Acknowledgments:

Name: the Pidgin project Upstream: Jacob Appelbaum, Moxie Marlinspike

The pidginconvchatrenameuser function in gtkconv.c in Pidgin before 2.10.2 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by changing a nickname while in an XMPP chat room.

The UPnP functionality in Pidgin 2.0.0, and possibly other versions, allows remote attackers to trigger the download of arbitrary files and cause a denial of service (memory or disk consumption) via a UDP packet that specifies an arbitrary URL.

A NULL pointer dereference vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in a denial of service vulnerability. A malicious server can send a packet starting with a NULL byte triggering the vulnerability.

A denial of service vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in an out-of-bounds read. A malicious server or user can send an invalid mood to trigger this vulnerability.

A denial of service vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in a null pointer dereference. A malicious server or an attacker who intercepts the network traffic can send invalid data to trigger this vulnerability and cause a crash.

A denial of service vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in an out-of-bounds read. A malicious server or an attacker who intercepts the network traffic can send invalid data to trigger this vulnerability and cause a crash.

An information leak exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in an out-of-bounds read. A malicious user, server, or man-in-the-middle can send an invalid size for an avatar which will trigger an out-of-bounds read vulnerability. This could result in a denial of service or copy data from memory to the file, resulting in an information leak if the avatar is sent to another user.

A denial of service vulnerability exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent from the server could potentially result in an out-of-bounds read. A malicious server or man-in-the-middle attacker can send invalid data to trigger this vulnerability.

An information leak exists in the handling of the MXIT protocol in Pidgin. Specially crafted MXIT data sent via the server could potentially result in an out-of-bounds read. A malicious user, server, or man-in-the-middle attacker can send an invalid size for a file transfer which will trigger an out-of-bounds read vulnerability. This could result in a denial of service or copy data from memory to the file, resulting in an information leak if the file is sent to another user.