gnutls: Uses incorrect cryptography for DTLS (CVE-2020-11501)

GnuTLS 3.6.x before 3.6.13 uses incorrect cryptography for DTLS. The earliest affected version is 3.6.3 (2018-07-16) because of an error in a 2017-10-06 commit. The DTLS client always uses 32 '\0' bytes instead of a random value, and thus contributes no randomness to a DTLS negotiation. This breaks the security guarantees of the DTLS protocol.

References:

• https://gitlab.com/gnutls/gnutls/-/issues/960
• https://nvd.nist.gov/vuln/detail/CVE-2020-11501
• Broken-by: https://gitlab.com/gnutls/gnutls/-/commit/bcf4de0371efbdf0846388e2df0cb14b5db09954 (gnutls_3_6_3)

Patch:

https://gitlab.com/gnutls/gnutls/-/commit/c01011c2d8533dbbbe754e49e256c109cb848d0d (3.6.13)

Affected branches:

• master
• 3.11-stable
• 3.10-stable
• 3.9-stable
• 3.8-stable