CVE-2020-13777

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

Updated gnutls packages fix security vulnerability:

It was found that GnuTLS 3.6.4 introduced a regression in the TLS protocol implementation. This caused the TLS server to not securely construct a session ticket encryption key considering the application supplied secret, allowing a MitM attacker to bypass authentication in TLS 1.3 and recover previous conversations in TLS 1.2 (CVE-2020-13777).

This update for gnutls fixes the following issues:

• CVE-2020-13777: Fixed an insecure session ticket key construction which could have made the TLS server to not bind the session ticket encryption key with a value supplied by the application until the initial key rotation, allowing an attacker to bypass authentication in TLS 1.3 and recover previous conversations in TLS 1.2 (bsc#1172506).
• Fixed an improper handling of certificate chain with cross-signed intermediate CA certificates (bsc#1172461).

This update was imported from the SUSE:SLE-15:Update update project.

These are all security issues fixed in the gnutls-3.7.2-1.2 package on the GA media of openSUSE Tumbleweed.

This update for gnutls fixes the following issues:

• CVE-2020-13777: Fixed an insecure session ticket key construction which could have made the TLS server to not bind the session ticket encryption key with a value supplied by the application until the initial key rotation, allowing an attacker to bypass authentication in TLS 1.3 and recover previous conversations in TLS 1.2 (bsc#1172506).
• Fixed an improper handling of certificate chain with cross-signed intermediate CA certificates (bsc#1172461).

It was discovered that GnuTLS incorrectly handled session ticket encryption keys. A remote attacker could possibly use this issue to bypass authentication or recover sensitive information.