Description: Some vulnerabilities have been reported in GnuTLS, which can be exploited by malicious people to cause a DoS (Denial of Service) or to potentially compromise an application using the library.
1) A boundary error exists in the processing "Client Hello" messages containing a "Server Name" extension. This can be exploited to cause a heap-based buffer overflow via a specially crafted TLS packet.
Successful exploitation may allow execution of arbitrary code.
2) A NULL-pointer dereference error in the processing of TLS packets containing multiple "Client Hello" messages can be exploited to crash an affected application.
3) A signedness error exists within the "_gnutls_ciphertext2compressed()" function in lib/gnutls_cipher.c. This can be exploited to cause an out of bounds read and crash an affected application via specially crafted, encrypted TLS data.
The vulnerabilities are reported in versions prior to 2.2.4.
Solution: Update to version 2.2.5 or apply patches (see vendor advisory for more details).
Provided and/or discovered by: Ossi Herrala and Jukka Taimisto from the CROSS project at Codenomicon. Reported via CERT-FI.
Changelog: 2008-05-21: Updated "Solution" section due to an error introduced in version 2.2.4. Updated "Original Advisory" section.
2008-05-30: Added links to US-CERT.
2008-06-02: Added link to US-CERT.
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