CVE-2016-7444

The gnutls_ocsp_resp_check_crt function in lib/x509/ocsp.c in GnuTLS before 3.4.15 and 3.5.x before 3.5.4 does not verify the serial length of an OCSP response, which might allow remote attackers to bypass an intended certificate validation mechanism via vectors involving trailing bytes left by gnutls_malloc.

The gnutls_ocsp_resp_check_crt function in lib/x509/ocsp.c in GnuTLS before 3.4.15 and 3.5.x before 3.5.4 does not verify the serial length of an OCSP response, which might allow remote attackers to bypass an intended certificate validation mechanism via vectors involving trailing bytes left by gnutls_malloc.

An issue was found in certificate validation using OCSP responses caused by not verifying the serial length, which can falsely report a certificate as valid (CVE-2016-7444).

This update for gnutls fixes the following security issues:

• GnuTLS could have crashed when processing maliciously crafted OpenPGP certificates (GNUTLS-SA-2017-2, bsc#1018832, CVE-2017-5335, CVE-2017-5337, CVE-2017-5336)
• GnuTLS could have falsely accepted certificates when using OCSP (GNUTLS-SA-2016-3, bsc#999646, CVE-2016-7444)
• GnuTLS could have suffered from 100% CPU load DoS attacks by using SSL alert packets during the handshake (bsc#1005879, CVE-2016-8610)

Stefan Buehler discovered that GnuTLS incorrectly verified the serial length of OCSP responses. A remote attacker could possibly use this issue to bypass certain certificate validation measures. This issue only applied to Ubuntu 16.04 LTS. (CVE-2016-7444)

Shi Lei discovered that GnuTLS incorrectly handled certain warning alerts. A remote attacker could possibly use this issue to cause GnuTLS to hang, resulting in a denial of service. This issue has only been addressed in Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2016-8610)

It was discovered that GnuTLS incorrectly decoded X.509 certificates with a Proxy Certificate Information extension. A remote attacker could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. This issue only affected Ubuntu 16.04 LTS and Ubuntu 16.10. (CVE-2017-5334)

It was discovered that GnuTLS incorrectly handled certain OpenPGP certificates. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2017-5335, CVE-2017-5336, CVE-2017-5337)