# CVE-2026-31946: OpenOLAT: Authentication bypass via forged JWT in OIDC implicit flow

> Attackers can bypass authentication in OpenOLAT by forging JWTs in the OIDC implicit flow, gaining unauthorized access to user accounts.

- **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:** 30 Mar 2026
- **Updated:** 31 Mar 2026
- **Also known as:** GHSA-v8vp-x4q4-2vch

## What is CVE-2026-31946?

CVE-2026-31946 is a critical authentication bypass vulnerability in OpenOLAT, published on 30 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

OpenOlat is an open source web-based e-learning platform for teaching, learning, assessment and communication. From version 10.5.4 to before version 20.2.5, OpenOLAT's OpenID Connect implicit flow implementation does not verify JWT signatures. The JSONWebToken.parse() method silently discards the signature segment of the compact JWT (header.payload.signature), and the getAccessToken() methods in both OpenIdConnectApi and OpenIdConnectFullConfigurableApi only validate claim-level fields (issuer, audience, state, nonce) without any cryptographic signature verification against the Identity Provider's JWKS endpoint. This issue has been patched in version 20.2.5.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature), CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2026-31946?

It affects 1 product.


Products: Frentix Openolat.

## How do I fix CVE-2026-31946?

No fix has been published for CVE-2026-31946 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-31946 being exploited?

There is no known exploitation of CVE-2026-31946 in the wild and no public exploit code.

## Other vulnerabilities in OpenOLAT

- [CVE-2026-28228](https://insights.sbomify.com/CVE-2026-28228/): OpenOLAT: Server-Side Template Injection (SSTI) in Velocity templates allows Remote Code Execution (high 8.8)
- [CVE-2021-39181](https://insights.sbomify.com/CVE-2021-39181/): Unsafe Deserialization of User Data Using XStream (high 8.8)
- [CVE-2021-41242](https://insights.sbomify.com/CVE-2021-41242/): Path Traversal in some REST methods leading to file upload to arbitrary places (high 8.1)
- [CVE-2021-39180](https://insights.sbomify.com/CVE-2021-39180/): Path Traversal in Archive Handling Leading to Code Execution (high 8.1)
- [CVE-2021-41152](https://insights.sbomify.com/CVE-2021-41152/): Path Traversal in Folder Component Leading to Local File Inclusion (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31946 and fix it if it is affected.

What it is: CVE-2026-31946 is a critical authentication bypass vulnerability in OpenOLAT, published on 30 Mar 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-2026-31946 in the wild and no public exploit code.

Affected product: OpenOLAT. 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-2026-31946/ (Markdown: https://insights.sbomify.com/CVE-2026-31946/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31946
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31946
- OSV: https://osv.dev/vulnerability/CVE-2026-31946

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31946/
Summaries are generated and may contain mistakes; the official description above is the record.