# CVE-2026-86304: MojoX::Authentication versions before 0.006 for Perl allow SAML authentication bypass because parse_assertion builds Net::SAML2::Binding::PO

> Attackers can bypass SAML authentication in MojoX::Authentication by submitting forged responses, leading to unauthorized account access.

- **Severity:** Critical 9.8 (`CVSS:3.1/AV:N/AC:L/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:** 6 Sep 2026
- **Updated:** 8 Sep 2026
- **Also known as:** GHSA-34pg-3x4x-4vf5

## What is CVE-2026-86304?

CVE-2026-86304 is a critical authentication bypass vulnerability, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

MojoX::Authentication versions before 0.006 for Perl allow SAML authentication bypass because parse_assertion builds Net::SAML2::Binding::POST without a trust anchor.

parse_assertion in MojoX::Authentication::Model::SAML2 calls Net::SAML2::Binding::POST->new with no cacert, cert_text or anchors argument, then passes the returned XML to Net::SAML2::Protocol::Assertion->new_from_xml with the IdP signing certificate as cacert. In Net::SAML2 before 0.86 that certificate guards only encrypted assertions, so the signature on an unencrypted assertion is checked against the certificate the response itself carries.

An attacker starts a SAML login, then posts a response signed with a certificate of their own. The audience, InResponseTo and timestamp checks that follow are all satisfiable by the attacker, so the response authenticates any NameID it carries.

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

## Which versions are affected by CVE-2026-86304?


## How do I fix CVE-2026-86304?

No fix has been published for CVE-2026-86304 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86304 being exploited?

There is no known exploitation of CVE-2026-86304 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86304 and fix it if it is affected.

What it is: CVE-2026-86304 is a critical authentication bypass vulnerability, published on 6 Sep 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-2026-86304 in the wild and no public exploit code.

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-2026-86304/ (Markdown: https://insights.sbomify.com/CVE-2026-86304/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86304
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86304
- OSV: https://osv.dev/vulnerability/CVE-2026-86304

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86304/
Summaries are generated and may contain mistakes; the official description above is the record.