# CVE-2002-1336: Auth bypass in n/a

> Remote attackers can bypass VNC authentication by sniffing reused challenge strings, allowing unauthorized access to the server.

- **Severity:** High 7.5 (`AV:N/AC:L/Au:N/C:P/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Sep 2004
- **Updated:** 8 Aug 2024
- **Also known as:** DEBIAN-CVE-2002-1336, GHSA-fcjm-23wr-m9g6

## What is CVE-2002-1336?

CVE-2002-1336 is a high-severity authentication bypass vulnerability in n/a, published on 1 Sep 2004. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

TightVNC before 1.2.6 generates the same challenge string for multiple connections, which allows remote attackers to bypass VNC authentication by sniffing the challenge and response of other users.

## Which versions are affected by CVE-2002-1336?

It affects 1 product.


Products: Tightvnc Tightvnc.

## How do I fix CVE-2002-1336?

Upgrade to a fixed version.

## Is CVE-2002-1336 being exploited?

There is no known exploitation of CVE-2002-1336 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2009-0388](https://insights.sbomify.com/CVE-2009-0388/): Integer overflow in n/a (critical 10.0)
- [CVE-2021-42785](https://insights.sbomify.com/CVE-2021-42785/): Buffer Overflow in tvnviewer.exe via Crafted Packet in TightVNC Viewer 2.8.59 (critical 9.8)
- [CVE-2019-15678](https://insights.sbomify.com/CVE-2019-15678/): Memory corruption in TightVNC (critical 9.8)
- [CVE-2019-15679](https://insights.sbomify.com/CVE-2019-15679/): Memory corruption in TightVNC (critical 9.8)
- [CVE-2019-8287](https://insights.sbomify.com/CVE-2019-8287/): Memory corruption in TightVNC (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2002-1336 and fix it if it is affected.

What it is: CVE-2002-1336 is a high-severity authentication bypass vulnerability in n/a, published on 1 Sep 2004. 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-2002-1336 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-2002-1336/ (Markdown: https://insights.sbomify.com/CVE-2002-1336/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2002-1336
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2002-1336
- OSV: https://osv.dev/vulnerability/CVE-2002-1336

---
From sbomify Insights: https://insights.sbomify.com/CVE-2002-1336/
Summaries are generated and may contain mistakes; the official description above is the record.