Apache WSS4J: Authentication bypass via forged SAML sender-vouches assertion
Summary
Apache WSS4J, a Java library for Web Services Security, contains an authentication bypass in its DOM security processor. An unauthenticated remote attacker can send a crafted, unsigned SAML sender-vouches assertion containing an attacker-controlled key and thereby forge authenticated SOAP messages. The CVSS base score is 9.8 (Critical); exposure depends on whether a Java application using the vulnerable library accepts SAML sender-vouches tokens.
Affected
- Apache WSS4J 4.0.0 before 4.0.2
- Apache WSS4J 3.0.0 before 3.0.6
- Apache WSS4J before 2.4.4
- Maven artifact: org.apache.wss4j:wss4j-ws-security-dom
Fixed in
- Apache WSS4J 4.0.2
- Apache WSS4J 3.0.6
- Apache WSS4J 2.4.4
- Distribution packages: Unknown (Ubuntu status 'Needs evaluation', Debian urgency not yet assigned)
Workaround
Unknown. No vendor-published workaround is known; upgrading is the stated remedy.
Exploitation
- No confirmed exploitation known at the time of research.
- No public proof-of-concept exploit known.
- CISA SSVC assessment: Exploitation none, Automatable yes, Technical Impact total.
- Listing in the CISA KEV catalog: Unknown (not verified).
Our recommendation
- Inventory Java applications and dependencies that use wss4j-ws-security-dom, including transitive dependencies (for example via Apache CXF).
- Upgrade to WSS4J 4.0.2, 3.0.6 or 2.4.4, matching your branch; ask vendors of appliances or bundled software for their fixed build.
- Prioritise internet-facing SOAP services and services that accept SAML tokens from partners.
- Monitor the Apache advisory and the CISA KEV catalog for changes.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Apache oss-security post CVE-2026-88920 www.openwall.com
- Apache advisory thread lists.apache.org
- Apache WSS4J 4.0.2 release github.com
- Apache WSS4J project site ws.apache.org
- Ubuntu security CVE-2026-88920 ubuntu.com
- Quarkus CXF 3.40.2 release notes docs.quarkiverse.io
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 30 Oct 2026, 21:54.
Original description (NVD)
An authentication bypass in the DOM security processor in Apache WSS4J allows unauthenticated remote attackers to forge authenticated SOAP messages via a crafted unsigned SAML sender-vouches assertion containing an attacker-controlled key. Users are recommended to upgrade to versions 4.0.2 or 3.0.6 or 2.4.4, which fix this issue.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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