# CVE-2021-36368: Security feature bypass in n/a

> OpenSSH users with agent forwarding may be unable to distinguish between local and remote authentication prompts, potentially allowing unauthorized access.

- **Severity:** Low 3.7 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/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:** 12 Mar 2022
- **Updated:** 29 May 2026
- **Also known as:** ALPINE-CVE-2021-36368, AZL-9045, DEBIAN-CVE-2021-36368, GHSA-542x-jxrc-hw4x

## What is CVE-2021-36368?

CVE-2021-36368 is a low-severity vulnerability in Debian Debian Linux, published on 12 Mar 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in OpenSSH before 8.9. If a client is using public-key authentication with agent forwarding but without -oLogLevel=verbose, and an attacker has silently modified the server to support the None authentication option, then the user cannot determine whether FIDO authentication is going to confirm that the user wishes to connect to that server, or that the user wishes to allow that server to connect to a different server on the user's behalf. NOTE: the vendor's position is "this is not an authentication bypass, since nothing is being bypassed.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-36368?

It affects 2 products.


Products: Debian Debian Linux, OpenSSH.

## How do I fix CVE-2021-36368?

Upgrade to a fixed version.

## Is CVE-2021-36368 being exploited?

There is no known exploitation of CVE-2021-36368 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-36368 and fix it if it is affected.

What it is: CVE-2021-36368 is a low-severity vulnerability in Debian Debian Linux, published on 12 Mar 2022. 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-2021-36368 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2021-36368/ (Markdown: https://insights.sbomify.com/CVE-2021-36368/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-36368
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-36368
- OSV: https://osv.dev/vulnerability/CVE-2021-36368

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-36368/
Summaries are generated and may contain mistakes; the official description above is the record.