CVE-2026-92899: apache software foundation apache wss4j Authentication Bypass by Spoofing

Vulnerability summary

CVE-2026-92899 is a medium (CVSS 4.8) Authentication Bypass by Spoofing vulnerability in apache software foundation apache wss4j. EPSS estimates a 0.51% chance of exploitation in the next 30 days, higher than 42.1% of scored vulnerabilities.

Timeline

1. 30-09-2026
   PublishedVulnerability first disclosed.
2. 30-09-2026
   Last modifiedVulnerability information updated.

Description

Apache WSS4J remembers the Nonce of each UsernameToken it accepts, so a captured token cannot be reused. It stored the Nonce as raw base64 text, but authentication decodes that text and uses the bytes.The same bytes can be written as base64 in several ways. An attacker who captured an authenticated request could re-send it with a space added to the Nonce: the password digest still verified, but the token no longer matched the remembered one, so the replay was accepted. Since a UsernameToken does not cover the message body, the captured token could then be reused on requests of the attacker's choosing until it expired. Affects deployments with a nonce replay cache configured, as Apache CXF has by default, and only tokens using a password digest. The cache is now keyed on the decoded Nonce. Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.

• CWE-290Authentication Bypass by SpoofingThis attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.