CVE-2020-13777: High severity gnutls vulnerability
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.
Other sources
GnuTLS servers are able to use tickets issued by each other without access to the secret key as generated by gnutlssessionticketkeygenerate(). In TLS 1.3 this allows a MITM server without valid credentials to resume sessions with a client that first established an initial connection with a server with valid credentials. In TLS 1.2, it may allow attackers to recover the previous conversations.
Reference: https://gitlab.com/gnutls/gnutls/-/issues/1011
— Red Hat
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2020-13777?
CVE-2020-13777 is a vulnerability in GnuTLS 3.6.x before 3.6.14 that uses incorrect cryptography for encrypting a session ticket, resulting in a loss of confidentiality in TLS 1.2 and an authentication bypass in TLS 1.3.
What is the severity of CVE-2020-13777?
The severity of CVE-2020-13777 is high with a severity value of 7.4.
Which software versions are affected by CVE-2020-13777?
GnuTLS versions before 3.6.14 are affected by CVE-2020-13777.
How do I fix CVE-2020-13777?
To fix CVE-2020-13777, update GnuTLS to version 3.6.14 or later.
Where can I find more information about CVE-2020-13777?
You can find more information about CVE-2020-13777 on the following links: - [GitLab](https://gitlab.com/gnutls/gnutls/-/issues/1011) - [Debian Security Tracker](https://security-tracker.debian.org/tracker/CVE-2020-13777) - [CVE Mitre](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-13777)