Scientific Linux Security Update : krb5 on SL5.x i386/x86_64
Medium Nessus Plugin ID 61266
SynopsisThe remote Scientific Linux host is missing one or more security updates.
DescriptionKerberos 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).
It was found that ftpd, a Kerberos-aware FTP server, did not properly drop privileges. On Scientific 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. (CVE-2011-1526)
This update also fixes the following bugs :
- 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.
- 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.
- 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.
- 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.
- 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.
SolutionUpdate the affected packages.