Apache CXF: Authentication bypass via hash collisions in STS token cache
Summary
Apache CXF's STSTokenValidator and Security Token Service cache validated security tokens under a non-cryptographic 32-bit hash. A cache hit is treated as proof that a token was already validated, so an attacker who crafts a colliding token (for example a UsernameToken or a self-signed SAML Assertion) can be accepted without password, signature or STS checks. This can lead to authentication as another user and to STS-signed tokens for that identity. The CVSS base score is 9.1 (critical), and the attack requires no privileges or user interaction.
Affected
- Apache CXF 4.2.0 before 4.2.4
- Apache CXF 4.0.0 before 4.1.9
- Apache CXF before 3.6.13
- Older branches (3.4.x, 3.5.x) are not listed in Apache's ranges; whether they are affected is unknown.
Fixed in
- Apache CXF 4.2.4
- Apache CXF 4.1.9 (also covers 4.0.x, as no separate 4.0.x fix exists)
- Apache CXF 3.6.13
Workaround
Unknown. Apache only documents upgrading as the remedy.
Exploitation
- Exploited in the wild: none reported in the sources reviewed.
- CISA SSVC assessment: Exploitation none, Automatable yes, Technical Impact total.
- Public proof of concept: none known.
Our recommendation
- Identify applications that use the cxf-rt-ws-security module, especially STSTokenValidator or STS token validation.
- Upgrade to CXF 4.2.4, 4.1.9 or 3.6.13 and rebuild and redeploy packaged applications, since updating the host alone may leave the vulnerable copy in place.
- Restrict access to affected services and monitor authentication logs for unusual token use until the update is applied.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Apache CXF security advisories cxf.apache.org
- Apache lists thread for CVE-2026-97468 lists.apache.org
- oss-security advisory CVE-2026-97468 www.openwall.com
- Apache CXF advisory mirror (users list) www.mail-archive.com
- HeroDevs vulnerability directory entry www.herodevs.com
- Linux Security news on Apache CXF fixes linuxsecurity.com
- WildFly pull request upgrading to CXF 4.1.9 github.com
- Qlik CXF WS-Security runtime token caching help.qlik.com
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 31 Oct 2026, 07:06.
Original description (NVD)
Apache CXF's STSTokenValidator and Security Token Service (STS) cached validated security tokens under a non-cryptographic 32-bit hash of the token (Java Arrays.hashCode/hashCode()), and treated a cache hit as proof that the presented token had already been validated. An attacker could craft a token (for example a UsernameToken or a self-signed SAML Assertion) whose hash collides with a cached entry. The token would then be accepted without password validation, signature trust verification or a call to the STS. This could let the attacker authenticate as another user and, through STS token validation or renewal, obtain STS-signed tokens for that identity. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, 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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