CVE-2020-5913: 
F5 BIG-IP Advanced Firewall Manager vulnerability analysis and mitigation

CVE-2020-5913 is a security vulnerability affecting F5 BIG-IP systems that was discovered in 2020. The vulnerability exists in the BIG-IP Client or Server SSL profile where revoked certificates are ignored, even when a valid Certificate Revocation List (CRL) is present. This issue affects multiple versions of BIG-IP including 15.0.0-15.1.0.1, 14.1.0-14.1.2.3, 13.1.0-13.1.3.4, 12.1.0-12.1.5.1, and 11.6.1-11.6.5.2 (MITRE CVE).

The vulnerability stems from a flaw in the SSL/TLS connection handling where the BIG-IP Client or Server SSL profile fails to properly validate certificate revocation status. Even in cases where a valid Certificate Revocation List is present, the system does not properly enforce certificate revocation checks (NVD).

The primary impact of this vulnerability is that it could potentially allow for man-in-the-middle attacks on SSL/TLS connections. Since revoked certificates are not properly validated, an attacker could potentially exploit this weakness to intercept and manipulate secure communications (MITRE CVE).

F5 has addressed this vulnerability by releasing patched versions of the affected software. Users are advised to upgrade to the appropriate fixed versions as detailed in the F5 support article (F5 Support).