Topic

An update for gnutls is now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having a security impact of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

The gnutls packages provide the GNU Transport Layer Security (GnuTLS) library, which implements cryptographic algorithms and protocols such as SSL, TLS, and DTLS.

The following packages have been upgraded to a later upstream version: gnutls (2.12.23). (BZ#1321112, BZ#1326073, BZ#1415682, BZ#1326389)

Security Fix(es):

• A denial of service flaw was found in the way the TLS/SSL protocol defined processing of ALERT packets during a connection handshake. A remote attacker could use this flaw to make a TLS/SSL server consume an excessive amount of CPU and fail to accept connections form other clients. (CVE-2016-8610)
• Multiple flaws were found in the way gnutls processed OpenPGP certificates. An attacker could create specially crafted OpenPGP certificates which, when parsed by gnutls, would cause it to crash. (CVE-2017-5335, CVE-2017-5336, CVE-2017-5337)

Additional Changes:

For detailed information on changes in this release, see the Red Hat Enterprise Linux 6.9 Release Notes and Red Hat Enterprise Linux 6.9 Technical Notes linked from the References section.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux Server 6 x86_64
• Red Hat Enterprise Linux Server 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support 6 i386
• Red Hat Enterprise Linux Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• Red Hat Enterprise Linux Desktop 6 x86_64
• Red Hat Enterprise Linux Desktop 6 i386
• Red Hat Enterprise Linux for IBM z Systems 6 s390x
• Red Hat Enterprise Linux for Power, big endian 6 ppc64
• Red Hat Enterprise Linux for Scientific Computing 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x

Fixes

• BZ - 1320982 - ASSERT failure in gnutls-cli-debug
• BZ - 1321112 - DHE_DSS ciphers don't work with client certificates and OpenSSL using TLSv1.2
• BZ - 1323215 - gnutls-serv --http crashes with client certificates with NSS client
• BZ - 1326073 - GnuTLS prefers SHA-1 signatures in TLSv1.2
• BZ - 1326389 - GnuTLS server does not accept SHA-384 and SHA-512 Certificate Verify signatures despite advertising support for them
• BZ - 1326886 - GnuTLS server rejects connections that do not advertise support for SHA-1 signature algorithms
• BZ - 1327656 - gnutls-serv: closing connection without sending an Alert message
• BZ - 1328205 - gnutls-cli won't send certificates that don't match hashes in Certificate Request
• BZ - 1333521 - Provide ability to set the expected server name in gnutls-serv utility
• BZ - 1335924 - gnutls: Disable TLS connections with less than 1024-bit DH parameters
• BZ - 1337460 - Disable/remove export ciphersuites in GnuTLS
• BZ - 1384743 - CVE-2016-8610 SSL/TLS: Malformed plain-text ALERT packets could cause remote DoS
• BZ - 1411836 - CVE-2017-5337 gnutls: Heap read overflow in read-packet.c
• BZ - 1412235 - CVE-2017-5335 gnutls: Out of memory while parsing crafted OpenPGP certificate
• BZ - 1412236 - CVE-2017-5336 gnutls: Stack overflow in cdk_pk_get_keyid
• BZ - 1415682 - Changes introduced by rebase to 2.12.23 break API and ABI compatibility for some libraries

CVEs

• CVE-2016-8610
• CVE-2017-5335
• CVE-2017-5336
• CVE-2017-5337

References

• https://access.redhat.com/security/updates/classification/#moderate
• https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/6.9_Release_Notes/index.html
• https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/6.9_Technical_Notes/index.html