The remote Scientific Linux host is missing one or more security
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).
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
- 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
All users of krb5 are advised to upgrade to these updated packages,
which resolve these issues.
See also :
Update the affected packages.
Risk factor :
Medium / CVSS Base Score : 6.5