RHSA-2015:1457 - Security Advisory

Topic

Updated gnutls packages that fix three security issues and one bug are now
available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Moderate security
impact. Common Vulnerability Scoring System (CVSS) base scores, which give
detailed severity ratings, are available for each vulnerability from the
CVE links in the References section.

Description

The GnuTLS library provides support for cryptographic algorithms and for
protocols such as Transport Layer Security (TLS).

It was found that GnuTLS did not check activation and expiration dates of
CA certificates. This could cause an application using GnuTLS to
incorrectly accept a certificate as valid when its issuing CA is already
expired. (CVE-2014-8155)

It was found that GnuTLS did not verify whether a hashing algorithm listed
in a signature matched the hashing algorithm listed in the certificate.
An attacker could create a certificate that used a different hashing
algorithm than it claimed, possibly causing GnuTLS to use an insecure,
disallowed hashing algorithm during certificate verification.
(CVE-2015-0282)

It was discovered that GnuTLS did not check if all sections of X.509
certificates indicate the same signature algorithm. This flaw, in
combination with a different flaw, could possibly lead to a bypass of the
certificate signature check. (CVE-2015-0294)

The CVE-2014-8155 issue was discovered by Marcel Kolaja of Red Hat.
The CVE-2015-0282 and CVE-2015-0294 issues were discovered by Nikos
Mavrogiannopoulos of the Red Hat Security Technologies Team.

This update also fixes the following bug:

• Previously, under certain circumstances, the certtool utility could

generate X.509 certificates which contained a negative modulus.
Consequently, such certificates could have interoperation problems with the
software using them. The bug has been fixed, and certtool no longer
generates X.509 certificates containing a negative modulus. (BZ#1036385)

Users of gnutls are advised to upgrade to these updated packages, which
contain backported patches to correct these issues.

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

For details on how to apply this update, 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 Workstation 6 x86_64
• Red Hat Enterprise Linux Workstation 6 i386
• 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 from RHUI 6 x86_64
• Red Hat Enterprise Linux Server from RHUI 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 Desktop 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support (for IBM z Systems) 6 s390x
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 x86_64
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension 6 i386
• Red Hat Enterprise Linux Server - Extended Life Cycle Support Extension (for IBM z Systems) 6 s390x

Fixes

• BZ - 1036385 - Certtool generates x509 certificates which contain negative modulus
• BZ - 1194371 - CVE-2015-0282 gnutls: RSA PKCS#1 signature verification forgery
• BZ - 1196323 - CVE-2015-0294 gnutls: certificate algorithm consistency checking issue
• BZ - 1197995 - CVE-2014-8155 gnutls: gnutls does not perform date/time checks on CA certificates

CVEs

• CVE-2014-8155
• CVE-2015-0282
• CVE-2015-0294

References

• https://access.redhat.com/security/updates/classification/#moderate