# CVE-2026-87004: Tugtainer: OIDC id_token claims accepted without signature/audience/expiry verification

> Attackers can bypass OIDC authentication in Tugtainer by forging unsigned id_tokens, gaining unauthorized access to the container automation platform.

- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 30 Sep 2026
- **Updated:** 30 Sep 2026
- **Also known as:** GHSA-crjc-6vc7-xrfh

## What is CVE-2026-87004?

CVE-2026-87004 is a high-severity authentication bypass vulnerability in Quenary tugtainer, published on 30 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Tugtainer is a self-hosted app for automating updates of Docker containers. Prior to version 1.31.3, when the OIDC login flow completes, backend/modules/auth/providers/auth_oidc_provider.py decodes the id_token returned by the identity provider's token endpoint using jose.jwt.get_unverified_claims() instead of jwt.decode(). This skips signature verification, audience (aud) validation, issuer (iss) validation, and expiry (exp) checking entirely. The extracted claims (email/sub/preferred_username) are then used directly as the user_id for the resulting Tugtainer session. This issue has been patched in version 1.31.3.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-87004?


## How do I fix CVE-2026-87004?

No fix has been published for CVE-2026-87004 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-87004 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87004 exists.

Public exploit code:

- PoC — OIDC id_token accepted without signature/audience/expiry check in Tugtainer (GHSA-crjc-6vc7-xrfh, CVE-2026-87004, CVSS 8.1). (github_poc): https://github.com/squeeze440/tugtainer-PoC

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-87004 and fix it if it is affected.

What it is: CVE-2026-87004 is a high-severity authentication bypass vulnerability in Quenary tugtainer, published on 30 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-87004 exists.

Affected product: Quenary tugtainer. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-87004/ (Markdown: https://insights.sbomify.com/CVE-2026-87004/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-87004
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-87004
- OSV: https://osv.dev/vulnerability/CVE-2026-87004

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-87004/
Summaries are generated and may contain mistakes; the official description above is the record.