# CVE-2026-13089: Auth bypass in OIDC::Lite

> Attackers can bypass ID Token signature verification in OIDC::Lite by manipulating the algorithm header, allowing authentication as any user.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Jul 2026
- **Updated:** 27 Jul 2026
- **Also known as:** GHSA-fr32-wcm4-p6hf

## What is CVE-2026-13089?

CVE-2026-13089 is a high-severity authentication bypass vulnerability in RITOU OIDC::Lite, published on 22 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OIDC::Lite versions through 0.12.1 for Perl allow ID Token signature verification bypass via a token-controlled algorithm allowlist in verify.

When the caller does not pin an algorithm, OIDC::Lite::Model::IDToken::verify sets $self->alg($self->header->{alg}) from the token's own header and then calls decode_jwt(token, key, 1, [$self->alg]), handing JSON::WebToken an accepted-algorithm allowlist taken from the untrusted token. A token with alg=none yields ['none'], so decode_jwt returns the claims with no signature check, and a token with alg=HS256 is verified with the RP's RSA public key as the HMAC secret (RS to HS confusion).

The ID Token is the OpenID Connect authentication assertion delivered to the Relying Party. Any caller that verifies an ID Token through the unpinned load(token)->verify path, or load(token, key) with only the key pinned, accepts a forged token carrying attacker-chosen claims such as sub and is authenticated as any user. Passing an explicit algorithm so $self->alg is already set bypasses the header-derived allowlist and is not affected.

Note that the latest version uploaded to CPAN is 0.10. Later versions are available in the git repository.

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

## Which versions are affected by CVE-2026-13089?


## How do I fix CVE-2026-13089?

No fix has been published for CVE-2026-13089 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-13089 being exploited?

There is no known exploitation of CVE-2026-13089 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-13089 and fix it if it is affected.

What it is: CVE-2026-13089 is a high-severity authentication bypass vulnerability in RITOU OIDC::Lite, published on 22 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-13089 in the wild and no public exploit code.

Affected product: RITOU OIDC::Lite. 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-2026-13089/ (Markdown: https://insights.sbomify.com/CVE-2026-13089/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-13089
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-13089
- OSV: https://osv.dev/vulnerability/CVE-2026-13089

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-13089/
Summaries are generated and may contain mistakes; the official description above is the record.