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centosCentOS ProjectCESA-2016:0176
HistoryFeb 17, 2016 - 1:37 a.m.

glibc, nscd security update

2016-02-1701:37:20
CentOS Project
lists.centos.org
40

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

6.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.974 High

EPSS

Percentile

99.9%

CentOS Errata and Security Advisory CESA-2016:0176

The glibc packages provide the standard C libraries (libc), POSIX
thread libraries (libpthread), standard math libraries (libm), and the
name service cache daemon (nscd) used by multiple programs on the
system. Without these libraries, the Linux system cannot function
correctly.

A stack-based buffer overflow was found in the way the libresolv library
performed dual A/AAAA DNS queries. A remote attacker could create a
specially crafted DNS response which could cause libresolv to crash or,
potentially, execute code with the permissions of the user running the
library. Note: this issue is only exposed when libresolv is called from the
nss_dns NSS service module. (CVE-2015-7547)

It was discovered that the calloc implementation in glibc could return
memory areas which contain non-zero bytes. This could result in unexpected
application behavior such as hangs or crashes. (CVE-2015-5229)

The CVE-2015-7547 issue was discovered by the Google Security Team and Red
Hat. Red Hat would like to thank Jeff Layton for reporting the
CVE-2015-5229 issue.

This update also fixes the following bugs:

  • The existing implementation of the “free” function causes all memory
    pools beyond the first to return freed memory directly to the operating
    system as quickly as possible. This can result in performance degradation
    when the rate of free calls is very high. The first memory pool (the main
    pool) does provide a method to rate limit the returns via M_TRIM_THRESHOLD,
    but this method is not available to subsequent memory pools.

With this update, the M_TRIM_THRESHOLD method is extended to apply to all
memory pools, which improves performance for threads with very high amounts
of free calls and limits the number of “madvise” system calls. The change
also increases the total transient memory usage by processes because the
trim threshold must be reached before memory can be freed.

To return to the previous behavior, you can either set M_TRIM_THRESHOLD
using the “mallopt” function, or set the MALLOC_TRIM_THRESHOLD environment
variable to 0. (BZ#1298930)

  • On the little-endian variant of 64-bit IBM Power Systems (ppc64le), a bug
    in the dynamic loader could cause applications compiled with profiling
    enabled to fail to start with the error “monstartup: out of memory”.
    The bug has been corrected and applications compiled for profiling now
    start correctly. (BZ#1298956)

All glibc users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues.

Merged security bulletin from advisories:
https://lists.centos.org/pipermail/centos-announce/2016-February/083834.html

Affected packages:
glibc
glibc-common
glibc-devel
glibc-headers
glibc-static
glibc-utils
nscd

Upstream details at:
https://access.redhat.com/errata/RHSA-2016:0176

8.1 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

6.8 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

MEDIUM

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:M/Au:N/C:P/I:P/A:P

0.974 High

EPSS

Percentile

99.9%