# CVE-2011-10020: Kaillera 0.86 Server DoS via Malformed UDP Packet

> Unauthenticated remote attackers can crash the Kaillera server by sending malformed UDP packets after the initial handshake, causing service disruption.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 20 Aug 2025
- **Updated:** 15 May 2026
- **Also known as:** GHSA-r56f-c7p9-h5jg

## What is CVE-2011-10020?

CVE-2011-10020 is a high-severity denial of service vulnerability in Kaillera Project Server, published on 20 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Kaillera Server version 0.86 is vulnerable to a denial-of-service condition triggered by sending a malformed UDP packet after the initial handshake. Once a client sends a valid HELLO0.83 packet and receives a response, any subsequent malformed packet causes the server to crash and become unresponsive. This flaw stems from improper input validation in the server’s UDP packet handler, allowing unauthenticated remote attackers to disrupt service availability.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2011-10020?


## How do I fix CVE-2011-10020?

No fix has been published for CVE-2011-10020 yet. Limit exposure of the affected software until one is available.

## Is CVE-2011-10020 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2011-10020 exists.

Public exploit code:

- Kaillera 0.86 Server Denial of Service (metasploit)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-10020 and fix it if it is affected.

What it is: CVE-2011-10020 is a high-severity denial of service vulnerability in Kaillera Project Server, published on 20 Aug 2025. 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-2011-10020 exists.

Affected product: Kaillera Project Server. 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-2011-10020/ (Markdown: https://insights.sbomify.com/CVE-2011-10020/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-10020
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-10020
- OSV: https://osv.dev/vulnerability/CVE-2011-10020

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-10020/
Summaries are generated and may contain mistakes; the official description above is the record.