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4.80. krb5
Updated krb5 packages that fix one security issue are now available for Red Hat Enterprise Linux 4 and 5.
The Red Hat Security Response Team has rated this update as having Critical security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link associated with the description below.
Kerberos is a network authentication system which allows clients and servers to authenticate to each other using symmetric encryption and a trusted third-party, the Key Distribution Center (KDC).
Security Fix
- CVE-2011-4862
- A buffer overflow flaw was found in the MIT krb5 telnet daemon (telnetd). A remote attacker who can access the telnet port of a target machine could use this flaw to execute arbitrary code as root.
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 installed the krb5-workstation package, have enabled the telnet daemon, and have it accessible remotely, this update should be applied immediately.
All krb5-workstation users should upgrade to these updated packages, which contain a backported patch to correct this issue.
Updated krb5 packages that fix one security issue and various bugs are now available for Red Hat Enterprise Linux 5.
The Red Hat Security Response Team has rated this update as having low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link associated with the description below.
Kerberos is a network authentication system which allows clients and servers to authenticate to each other using symmetric encryption and a trusted third-party, the Key Distribution Center (KDC).
Security Fix
- CVE-2011-1526
- It was found that ftpd, a Kerberos-aware FTP server, did not properly drop privileges. On Red Hat Enterprise Linux 5, the ftpd daemon did not check for the potential failure of the effective group ID change system call. If the group ID change failed, a remote FTP user could use this flaw to gain unauthorized read or write access to files that are owned by the root group.
Red Hat would like to thank the MIT Kerberos project for reporting this issue. Upstream acknowledges Tim Zingelman as the original reporter.
Bug Fixes
- BZ#701444
- Due to a mistake in the Kerberos libraries, a client could fail to contact a Key Distribution Center (KDC) or terminate unexpectedly if the client had already more than 1024 file descriptors in use. This update backports modifications to the Kerberos libraries and the libraries use the poll() function instead of the select() function, as poll() does not have this limitation.
- BZ#708516
- The KDC failed to release memory when processing a TGS (ticket-granting server) request from a client if the client request included an authenticator with a subkey. As a result, the KDC consumed an excessive amount of memory. With this update, the code releasing the memory has been added and the problem no longer occurs.
- BZ#713500
- Under certain circumstances, if services requiring Kerberos authentication sent two authentication requests to the authenticating server, the second authentication request was flagged as a replay attack. As a result, the second authentication attempt was denied. This update applies an upstream patch that fixes this bug.
- BZ#729067
- Previously, if Kerberos credentials had expired, the klist command could terminate unexpectedly with a segmentation fault when invoked with the -s option. This happened when klist encountered and failed to process an entry with no realm name while scanning the credential cache. With this update, the underlying code has been modified and the command handles such entries correctly.
- BZ#735363, BZ#736132
- Due to a regression, multi-line FTP macros terminated prematurely with a segmentation fault. This occurred because the previously-added patch failed to properly support multi-line macros. This update restores the support for multi-line macros and the problem no longer occurs.
All users of krb5 are advised to upgrade to these updated packages, which resolve these issues.
