USN-2985-1: GNU C Library vulnerabilities

Ubuntu Security Notice USN-2985-1

25th May, 2016

eglibc, glibc vulnerabilities

A security issue affects these releases of Ubuntu and its derivatives:

• Ubuntu 15.10
• Ubuntu 14.04 LTS
• Ubuntu 12.04 LTS

Summary

Several security issues were fixed in the GNU C Library.

Software description

• eglibc - GNU C Library
• glibc - GNU C Library

Details

Martin Carpenter discovered that pt_chown in the GNU C Library did not
properly check permissions for tty files. A local attacker could use this
to gain administrative privileges or expose sensitive information.
(CVE-2013-2207, CVE-2016-2856)

Robin Hack discovered that the Name Service Switch (NSS) implementation in
the GNU C Library did not properly manage its file descriptors. An attacker
could use this to cause a denial of service (infinite loop).
(CVE-2014-8121)

Joseph Myers discovered that the GNU C Library did not properly handle long
arguments to functions returning a representation of Not a Number (NaN). An
attacker could use this to cause a denial of service (stack exhaustion
leading to an application crash) or possibly execute arbitrary code.
(CVE-2014-9761)

Arjun Shankar discovered that in certain situations the nss_dns code in the
GNU C Library did not properly account buffer sizes when passed an
unaligned buffer. An attacker could use this to cause a denial of service
or possibly execute arbitrary code. (CVE-2015-1781)

Sumit Bose and Lukas Slebodnik discovered that the Name Service
Switch (NSS) implementation in the GNU C Library did not handle long
lines in the files databases correctly. A local attacker could use
this to cause a denial of service (application crash) or possibly
execute arbitrary code. (CVE-2015-5277)

Adam Nielsen discovered that the strftime function in the GNU C Library did
not properly handle out-of-range argument data. An attacker could use this
to cause a denial of service (application crash) or possibly expose
sensitive information. (CVE-2015-8776)

Hector Marco and Ismael Ripoll discovered that the GNU C Library allowed
the pointer-guarding protection mechanism to be disabled by honoring the
LD_POINTER_GUARD environment variable across privilege boundaries. A local
attacker could use this to exploit an existing vulnerability more easily.
(CVE-2015-8777)

Szabolcs Nagy discovered that the hcreate functions in the GNU C Library
did not properly check its size argument, leading to an integer overflow.
An attacker could use to cause a denial of service (application crash) or
possibly execute arbitrary code. (CVE-2015-8778)

Maksymilian Arciemowicz discovered a stack-based buffer overflow in the
catopen function in the GNU C Library when handling long catalog names. An
attacker could use this to cause a denial of service (application crash) or
possibly execute arbitrary code. (CVE-2015-8779)

Florian Weimer discovered that the getnetbyname implementation in the GNU C
Library did not properly handle long names passed as arguments. An attacker
could use to cause a denial of service (stack exhaustion leading to an
application crash). (CVE-2016-3075)

Update instructions

The problem can be corrected by updating your system to the following package version:

Ubuntu 15.10:

libc6-dev 2.21-0ubuntu4.2

libc6 2.21-0ubuntu4.2

Ubuntu 14.04 LTS:

libc6-dev 2.19-0ubuntu6.8

libc6 2.19-0ubuntu6.8

Ubuntu 12.04 LTS:

libc6-dev 2.15-0ubuntu10.14

libc6 2.15-0ubuntu10.14

To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.

After a standard system update you need to reboot your computer to
make all the necessary changes.

References

CVE-2013-2207, CVE-2014-8121, CVE-2014-9761, CVE-2015-1781, CVE-2015-5277, CVE-2015-8776, CVE-2015-8777, CVE-2015-8778, CVE-2015-8779, CVE-2016-2856, CVE-2016-3075