CVE-2020-5929

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-09-25 · updated 2026-06-17
Weakness: CWE-203

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.

Affected products

F5 BIG-IP APM: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
BIG-IP: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Advanced Web Application Firewall: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Analytics: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Networks, Inc. BIG-IP (AAM): from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
BIG-IP ASM: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Ddos Hybrid Defender: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 BIG-IP DNS: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Fraud Protection Service: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Global Traffic Manager: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Big-Ip Link Controller: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 BIG-IP (LTM): from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 Networks, Inc. BIG-IP (PEM): from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2
F5 SSL Orchestrator: from 11.6.1 before 11.6.2; from 12.1.0 before 12.1.2; 11.6.2, 12.1.2, 12.1.2-hotfix1, 13.0.0, 13.0.0-hotfix1, 13.0.0-hotfix2 — fixed in 11.6.2, 12.1.2

How to fix

Upgrade to a fixed version: F5 BIG-IP APM 11.6.2, 12.1.2; BIG-IP 11.6.2, 12.1.2; F5 Big-Ip Advanced Web Application Firewall 11.6.2, 12.1.2; F5 Big-Ip Analytics 11.6.2, 12.1.2; F5 Networks, Inc. BIG-IP (AAM) 11.6.2, 12.1.2; BIG-IP ASM 11.6.2, 12.1.2; F5 Big-Ip Ddos Hybrid Defender 11.6.2, 12.1.2; F5 BIG-IP DNS 11.6.2, 12.1.2; F5 Big-Ip Fraud Protection Service 11.6.2, 12.1.2; F5 Big-Ip Global Traffic Manager 11.6.2, 12.1.2; F5 Big-Ip Link Controller 11.6.2, 12.1.2; F5 BIG-IP (LTM) 11.6.2, 12.1.2. Check the vendor advisory for mitigations.

References

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