Red Hat Bugzilla – Bug 1256686
CVE-2015-5224 util-linux: File name collision due to incorrect mkstemp use
Last modified: 2015-09-02 08:03:36 EDT
The following vulnerability in util-linux was announced (taken from http://seclists.org/oss-sec/2015/q3/423):
If the chfn and chsh binaries (both setuid-root) from
util-linux/login-utils are compiled WITHOUT libuser support, they
eventually call mkostemp(localtmp, O_RDWR|O_CREAT|O_EXCL|O_CLOEXEC);
where localtmp is "/etc/%s.XXXXXX" and %s is __progname (i.e., argv's
An attacker could repeatedly execve chfn as "ld.so" until mkostemp()
creates "/etc/ld.so.preload" (after a few days, in our tests). This
particular example doesn't actually work, because "preload" is 7 chars
and "XXXXXX" is 6 chars, but it seems there are other interesting
possibilities, like "/etc/rc.status" and "/etc/krb5.keytab".
The impact of this vulnerability is probably very limited: most Linux
distributions ship either the chfn/chsh binaries from the shadow-utils
(NOT the login-utils ones), or the login-utils ones but WITH libuser
Created util-linux tracking bugs for this issue:
Affects: fedora-all [bug 1256751]
We're not affected. Our binaries do not use the mkostemp function.
This issue did not affect the versions of util-linux as shipped with Red Hat Enterprise Linux 5 and 7. This issue does not affect the versions of util-linux-ng as shipped with Red Hat Enterprise Linux 6.