https://seclists.org/oss-sec/2026/q3/1026: CVE-2026-92899: Apache WSS4J: UsernameToken play protection bypassed by -encoding the Nonce

Q: Which deployments are affected?

Affected deployments have a UsernameToken nonce replay cache configured and accept UsernameToken authentication using a password digest. Apache CXF has a nonce replay cache enabled by default.

Q: What does an attacker need to exploit this issue?

An attacker needs to capture an authenticated request containing a password-digest UsernameToken. They can alter the base64 representation of the Nonce by adding a space while preserving the decoded bytes and valid password digest.

Q: What is the practical impact of a successful replay?

The captured token can be reused until it expires. Because the UsernameToken does not protect the message body, it can be used on requests chosen by the attacker.

Q: What should be done if the deployment is affected?

Upgrade Apache WSS4J to 4.0.2, 3.0.6, or 2.4.4, as appropriate for the deployed release line. These versions key the replay cache using the decoded Nonce.

Published Sep 30, 2026

Updated

Affected Software

1 affected component

Apache WSS4J>=4.0.0<4.0.2, >=3.0.0<3.0.6, <2.4.4

Frequently Asked Questions

Which deployments are affected?

Affected deployments have a UsernameToken nonce replay cache configured and accept UsernameToken authentication using a password digest. Apache CXF has a nonce replay cache enabled by default.

What does an attacker need to exploit this issue?

An attacker needs to capture an authenticated request containing a password-digest UsernameToken. They can alter the base64 representation of the Nonce by adding a space while preserving the decoded bytes and valid password digest.

What is the practical impact of a successful replay?

The captured token can be reused until it expires. Because the UsernameToken does not protect the message body, it can be used on requests chosen by the attacker.

What should be done if the deployment is affected?

Upgrade Apache WSS4J to 4.0.2, 3.0.6, or 2.4.4, as appropriate for the deployed release line. These versions key the replay cache using the decoded Nonce.