CVE-2020-5929: f5 big-ip_access_policy_manager Observable Discrepancy

Vulnerability summary

CVE-2020-5929 is a medium (CVSS 5.9) Observable Discrepancy vulnerability in f5 big-ip_access_policy_manager. EPSS estimates a 1.09% chance of exploitation in the next 30 days, higher than 64.9% of scored vulnerabilities.

Timeline

1. 25-09-2020
   PublishedVulnerability first disclosed.
2. 04-08-2024
   Last modifiedVulnerability information updated.

Description

In versions 13.0.0-13.0.0 HF2, 12.1.0-12.1.2 HF1, and 11.6.1-11.6.2, BIG-IP platforms with Cavium Nitrox SSL hardware acceleration cards, a Virtual Server configured with a Client SSL profile, and using Anonymous (ADH) or Ephemeral (DHE) Diffie-Hellman key exchange and Single DH use option not enabled in the options list may be vulnerable to crafted SSL/TLS Handshakes that may result with a PMS (Pre-Master Secret) that starts in a 0 byte and may lead to a recovery of plaintext messages as BIG-IP TLS/SSL ADH/DHE sends different error messages acting as an oracle. Similar error messages when PMS starts with 0 byte coupled with very precise timing measurement observation may also expose this vulnerability.

• CWE-203Observable DiscrepancyThe product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.