# CVE-2021-35473: Auth bypass in n/a

> Attackers can bypass authentication by using expired OAuth2.0 access tokens due to missing expiration checks in LemonLDAP::NG.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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:** Yes
- **Published:** 10 Nov 2024
- **Updated:** 19 Nov 2024
- **Also known as:** DEBIAN-CVE-2021-35473, GHSA-m833-cpj5-q368, UBUNTU-CVE-2021-35473

## What is CVE-2021-35473?

CVE-2021-35473 is a critical authentication bypass vulnerability in n/a, published on 10 Nov 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in LemonLDAP::NG before 2.0.12. There is a missing expiration check in the OAuth2.0 handler, i.e., it does not verify access token validity. An attacker can use a expired access token from an OIDC client to access the OAuth2 handler The earliest affected version is 2.0.4.

Weakness: CWE-613 (DEPRECATED: Insufficient Session Expiration)

## Which versions are affected by CVE-2021-35473?


## How do I fix CVE-2021-35473?

Upgrade to a fixed version.

## Is CVE-2021-35473 being exploited?

There is no known exploitation of CVE-2021-35473 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-35473 and fix it if it is affected.

What it is: CVE-2021-35473 is a critical authentication bypass vulnerability in n/a, published on 10 Nov 2024. 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-2021-35473 in the wild and no public exploit code.

Affected product: n/a. 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-2021-35473/ (Markdown: https://insights.sbomify.com/CVE-2021-35473/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-35473
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-35473
- OSV: https://osv.dev/vulnerability/CVE-2021-35473

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-35473/
Summaries are generated and may contain mistakes; the official description above is the record.