# CVE-2026-80465: Auth bypass in Mendix SAML (Mendix 10 compatible)

> Unauthenticated attackers can hijack accounts in specific SSO configurations due to improper SAML response signature validation.

- **Severity:** High 8.8 (`CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 3 Sep 2026
- **Updated:** 26 Oct 2026
- **Also known as:** GHSA-249p-r5w7-w969

## What is CVE-2026-80465?

CVE-2026-80465 is a high-severity authentication bypass vulnerability in Siemens Mendix SAML (Mendix 10 compatible), published on 3 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A vulnerability has been identified in Mendix SAML (Mendix 10 compatible) (All versions < V4.2.4), Mendix SAML (Mendix 11 compatible) (All versions < V4.2.4), Mendix SAML (Mendix 9.24 compatible) (All versions < V3.6.29). Affected versions of the module do not properly validate the SAML response signature. This could allow unauthenticated remote attackers to hijack an account (session) in specific SSO configurations.

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

## Which versions are affected by CVE-2026-80465?


## How do I fix CVE-2026-80465?

No fix has been published for CVE-2026-80465 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-80465 being exploited?

There is no known exploitation of CVE-2026-80465 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-80465 and fix it if it is affected.

What it is: CVE-2026-80465 is a high-severity authentication bypass vulnerability in Siemens Mendix SAML (Mendix 10 compatible), published on 3 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-80465 in the wild and no public exploit code.

Affected product: Siemens Mendix SAML (Mendix 10 compatible). 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-2026-80465/ (Markdown: https://insights.sbomify.com/CVE-2026-80465/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-80465
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-80465
- OSV: https://osv.dev/vulnerability/CVE-2026-80465

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-80465/
Summaries are generated and may contain mistakes; the official description above is the record.