Vulnerability Note VU#548487
BSD libc contains a buffer overflow vulnerability in link_ntoa()
The BSD libc library’s link_ntoa() function may be vulnerable to a classic buffer overflow. It is currently unclear if this issue is exploitable.
CWE-120: Buffer Copy without Checking Size of Input (‘Classic Buffer Overflow’) – CVE-2016-6559
Improper bounds checking of the obuf variable in the link_ntoa() function in linkaddr.c may allow an attacker to read or write from memory.
The full impact and severity depends on the method of exploit and how the library is used by applications. According to analysis by FreeBSD developers, it is very unlikely that applications exist that utilize link_ntoa() in an exploitable manner, and the CERT/CC is not aware of any proof of concept. A blog post describes the functionality of link_ntoa() and points out that none of the base utilities use this function in an exploitable manner. For more information, please see FreeBSD Security Advisory SA-16:37.
The CVSS score below reflects a worst-case scenario in which an attacker may execute arbitrary code with root permissions. It is unclear if any program exists that would allow exploit in any manner.
The full impact and severity depends on the method of exploit and how the library is used by applications. An attacker may be able to execute arbitrary code, but CERT/CC is currently unaware of a proof of concept.
Apply an update
FreeBSD libc was updated to address this vulnerability. Affected users are encouraged to upgrade to the latest version of libc and/or the latest release of your operating system.
In FreeBSD, the following patch levels (or later) contain a fix:
Vendor Information (Learn More)
|Vendor||Status||Date Notified||Date Updated|
|Apple||Affected||10 Oct 2016||16 Nov 2016|
|FreeBSD Project||Affected||21 Oct 2016||21 Nov 2016|
|HardenedBSD||Affected||26 Oct 2016||07 Dec 2016|
|NetBSD||Affected||26 Oct 2016||08 Dec 2016|
|DesktopBSD||Unknown||26 Oct 2016||26 Oct 2016|
|DragonFly BSD Project||Unknown||26 Oct 2016||26 Oct 2016|
|F5 Networks, Inc.||Unknown||26 Oct 2016||26 Oct 2016|
|Juniper Networks||Unknown||26 Oct 2016||26 Oct 2016|
|Nokia||Unknown||26 Oct 2016||26 Oct 2016|
|OpenBSD||Unknown||26 Oct 2016||08 Dec 2016|
|PC-BSD||Unknown||16 Nov 2016||16 Nov 2016|
|QNX Software Systems Inc.||Unknown||26 Oct 2016||26 Oct 2016|
|TrueOS||Unknown||16 Nov 2016||16 Nov 2016|
If you are a vendor and your product is affected, let
CVSS Metrics (Learn More)
Thanks to the reporter who wishes to remain anonymous.
This document was written by Garret Wassermann.
06 Dec 2016
Date First Published:
06 Dec 2016
Date Last Updated:
08 Dec 2016
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