[arch-security] [ASA-201501-4] libevent: heap overflow

[Remi Gacogne]

Arch Linux Security Advisory ASA-201501-4
=========================================

Severity: Medium
Date    : 2015-01-13
CVE-ID  : CVE-2014-6272
Package : libevent
Type    : heap overflow
Remote  : No
Link    : https://wiki.archlinux.org/index.php/CVE

Summary
=======

The package libevent before version 2.0.22-1 is vulnerable to a
potential heap overflow.

Resolution
==========

Upgrade to 2.0.22-1.

# pacman -Syu "libevent>=2.0.22-1"

The problem has been fixed upstream in version 2.0.22.

Workaround
==========

The potential heap overflow can be prevented by not using
evbuffer_add(), evbuffer_prepend(), evbuffer_expand(),
exbuffer_reserve_space(), or evbuffer_read() in a way leading to the use
of a buffer chunk larger than a single size_t.

Description
===========

A defect in the libevent evbuffer API could possibly leave some programs
that use the evbuffer API open to potential heap overflows. A program
using the evbuffer_add(), evbuffer_prepend(), evbuffer_expand(),
exbuffer_reserve_space(), or evbuffer_read() functions may be vulnerable
if an attacker is able to coax the linked program into trying to make a
buffer larger than that which would fit into a single size_t.

Impact
======

An attacker may be able to execute arbitrary code in a program using a
vulnerable version of libevent. Upstream has attempted to identify any
programs using libevent in a vulnerable way and has not as of yet found
any that do but, as a precaution, recommends upgrading.

References
==========

http://archives.seul.org/libevent/users/Jan-2015/msg00010.html
https://bugs.archlinux.org/task/43366
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2014-6272



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