REDHAT-BUG-600097: Race Condition
Dan Rosenberg reported that when MBX locking is enabled in exim, local users could exploit a race condition to change permissions of other non-root users' files. This could lead to a denial of service, to create new files owned by other users in unauthorized locations, or to possibly escalate privileges.
Further information is available from the upstream bug report [1] and this has been fixed upstream in exim 4.72 [2].
[1] http://bugs.exim.org/showbug.cgi?id=989 [2] http://vcs.exim.org/viewvc/exim/exim-src/src/transports/appendfile.c?r1=1.25&r2=1.26
While exim is built to support the MBX format, it is not the default for local mail delivery (Unix mailbox support is the default). This will only affect users that use the "mbxformat" option in the appendfile transport.
Affected Software
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-600097?
The severity of REDHAT-BUG-600097 is high due to the potential for denial of service and unauthorized file access.
How do I fix REDHAT-BUG-600097?
To fix REDHAT-BUG-600097, update Exim to the latest version beyond 4.72 where the vulnerability is addressed.
Which versions of Exim are affected by REDHAT-BUG-600097?
Exim versions up to but not including 4.72 are affected by REDHAT-BUG-600097.
What could an attacker potentially achieve by exploiting REDHAT-BUG-600097?
An attacker could potentially escalate privileges, create unauthorized files, or cause a denial of service by exploiting REDHAT-BUG-600097.
Is REDHAT-BUG-600097 a local or remote vulnerability?
REDHAT-BUG-600097 is a local vulnerability that requires local user access to exploit.