The GnuTLS library provides support for cryptographic algorithms and for protocols such as Transport Layer Security (TLS). GnuTLS includes libtasn1, a library developed for ASN.1 (Abstract Syntax Notation One) structures management that includes DER (Distinguished Encoding Rules) encoding and decoding.
A flaw was found in the way GnuTLS decrypted malformed TLS records. This could cause a TLS/SSL client or server to crash when processing a specially-crafted TLS record from a remote TLS/SSL connection peer. (CVE-2012-1573)
A flaw was found in the way libtasn1 decoded DER data. An attacker could create a carefully-crafted X.509 certificate that, when parsed by an application that uses GnuTLS, could cause the application to crash. (CVE-2012-1569)
A boundary error was found in the gnutls_session_get_data() function. A malicious TLS/SSL server could use this flaw to crash a TLS/SSL client or, possibly, execute arbitrary code as the client, if the client passed a fixed-sized buffer to gnutls_session_get_data() before checking the real size of the session data provided by the server. (CVE-2011-4128)
Red Hat would like to thank Matthew Hall of Mu Dynamics for reporting CVE-2012-1573 and CVE-2012-1569.
Users of GnuTLS are advised to upgrade to these updated packages, which contain backported patches to correct these issues. For the update to take effect, all applications linked to the GnuTLS library must be restarted, or the system rebooted.