# CVE-2022-25226: Auth bypass in ThinVNC

> Unauthenticated attackers can bypass authentication in ThinVNC to gain server access and execute arbitrary code via input events.

- **Severity:** Critical 10.0 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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:** 18 Apr 2022
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-mvv3-c6h9-hj2q

## What is CVE-2022-25226?

CVE-2022-25226 is a critical authentication bypass vulnerability in ThinVNC, published on 18 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

ThinVNC version 1.0b1 allows an unauthenticated user to bypass the authentication process via 'http://thin-vnc:8080/cmd?cmd=connect' by obtaining a valid SID without any kind of authentication. It is possible to achieve code execution on the server by sending keyboard or mouse events to the server.

## Which versions are affected by CVE-2022-25226?

It affects 1 product.


Products: Cybelsoft Thinvnc.

## How do I fix CVE-2022-25226?

No fix has been published for CVE-2022-25226 yet. Limit exposure of the affected software until one is available.

## Is CVE-2022-25226 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2022-25226 exists.

Public exploit code:

- ThinVNC 1.0b1 - Authentication Bypass to RCE (github_poc): https://github.com/krill-x7/CVE-2022-25226
- ThinVNC - Authentication Bypass (nuclei): http/cves/2022/CVE-2022-25226.yaml

## Other vulnerabilities in ThinVNC

- [CVE-2019-17662](https://insights.sbomify.com/CVE-2019-17662/): Path traversal in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-25226 and fix it if it is affected.

What it is: CVE-2022-25226 is a critical authentication bypass vulnerability in ThinVNC, published on 18 Apr 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2022-25226 exists.

Affected product: ThinVNC. 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-2022-25226/ (Markdown: https://insights.sbomify.com/CVE-2022-25226/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-25226
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-25226
- OSV: https://osv.dev/vulnerability/CVE-2022-25226

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-25226/
Summaries are generated and may contain mistakes; the official description above is the record.