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CVE Database

CVE-2011-4862

Impact: Critical
Public: 2011-12-25
CWE: CWE-130->CWE-119
Bugzilla: 770325: CVE-2011-4862 krb5: telnet client and server encrypt_keyid heap-based buffer overflow
IAVA: 2012-A-0056

Details

The MITRE CVE dictionary describes this issue as:

Buffer overflow in libtelnet/encrypt.c in telnetd in FreeBSD 7.3 through 9.0, MIT Kerberos Version 5 Applications (aka krb5-appl) 1.0.2 and earlier, Heimdal 1.5.1 and earlier, GNU inetutils, and possibly other products allows remote attackers to execute arbitrary code via a long encryption key, as exploited in the wild in December 2011.

Find out more about CVE-2011-4862 from the MITRE CVE dictionary and NIST NVD.

Statement

A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd) as shipped with all supported versions of Red Hat Enterprise Linux. A remote attacker who can access the telnet port of a target machine could use this flaw to execute arbitrary code as root.

While we are aware of public exploits for this issue that include targets for Red Hat Enterprise Linux 3, we are not aware of any yet which would be successful in gaining arbitrary root code execution in Red Hat Enterprise Linux 4, 5, or 6. However it is plausible that one could be created to do so.

Note that the krb5 telnet daemon is not enabled by default in any version of Red Hat Enterprise Linux. In addition, the default firewall rules block remote access to the telnet port. This flaw does not affect the telnet daemon distributed in the telnet-server package.

For users who have enabled the krb5 telnet daemon and have it accessible remotely, they should disable it or apply the updates we have released.

Since same encryption code is shared between the MIT krb5 telnet daemon and the telnet client, this issue affects the telnet client as well. The updates we have released fixes the issue for both, the telnet daemon and the telnet client.

CVSS v2 metrics

Base Score: 8.3
Base Metrics: AV:A/AC:L/Au:N/C:C/I:C/A:C
Access Vector: Adjacent Network
Access Complexity: Low
Authentication: None
Confidentiality Impact: Complete
Integrity Impact: Complete
Availability Impact: Complete

Find out more about Red Hat support for the Common Vulnerability Scoring System (CVSS).

Red Hat security errata

Platform Errata Release Date
Red Hat Enterprise Linux ES (v. 3 ELS) (krb5) RHSA-2011:1853 December 28, 2011
Red Hat Enterprise Linux EUS (v. 5.6 server) (krb5) RHSA-2011:1853 December 28, 2011
Red Hat Enterprise Linux Long Life (v. 5.3 server) (krb5) RHSA-2011:1853 December 28, 2011
Red Hat Enterprise Linux Server EUS (v. 6.0) (krb5-appl) RHSA-2011:1854 December 28, 2011
Red Hat Enterprise Linux Server EUS (v. 6.1) (krb5-appl) RHSA-2011:1854 December 28, 2011
Red Hat Enterprise Linux version 4 (krb5) RHSA-2011:1851 December 27, 2011
Red Hat Enterprise Linux version 5 (krb5) RHSA-2011:1851 December 27, 2011
Red Hat Enterprise Linux version 6 (krb5-appl) RHSA-2011:1852 December 27, 2011

External References

This page is generated automatically and has not been checked for errors or omissions.

For clarification or corrections please contact the Red Hat Security Response Team.