# CVE-2011-4939: Null dereference in n/a

> Remote attackers can crash Pidgin by changing nicknames in XMPP chats, causing a denial of service via null pointer dereference.

- **Severity:** Medium 6.4 (`AV:N/AC:L/Au:N/C:N/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Mar 2012
- **Updated:** 7 Aug 2024
- **Also known as:** DEBIAN-CVE-2011-4939, GHSA-fqpj-4v5c-wf35

## What is CVE-2011-4939?

CVE-2011-4939 is a medium-severity vulnerability in Pidgin Pidgin, published on 15 Mar 2012. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

The pidgin_conv_chat_rename_user function in gtkconv.c in Pidgin before 2.10.2 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by changing a nickname while in an XMPP chat room.

Weakness: CWE-264

## Which versions are affected by CVE-2011-4939?

It affects 1 product.


Products: Pidgin Pidgin.

## How do I fix CVE-2011-4939?

Upgrade to a fixed version.

## Is CVE-2011-4939 being exploited?

There is no known exploitation of CVE-2011-4939 in the wild and no public exploit code.

## Other vulnerabilities in Pidgin Pidgin

- [CVE-2013-6490](https://insights.sbomify.com/CVE-2013-6490/): Memory corruption in n/a (critical 10.0)
- [CVE-2016-1000030](https://insights.sbomify.com/CVE-2016-1000030/): Code injection in n/a (critical 9.8)
- [CVE-2013-6486](https://insights.sbomify.com/CVE-2013-6486/): Command injection in n/a (critical 9.3)
- [CVE-2011-3185](https://insights.sbomify.com/CVE-2011-3185/): Command injection in n/a (critical 9.3)
- [CVE-2009-1376](https://insights.sbomify.com/CVE-2009-1376/): Integer overflow in n/a (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-4939 and fix it if it is affected.

What it is: CVE-2011-4939 is a medium-severity vulnerability in Pidgin Pidgin, published on 15 Mar 2012. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2011-4939 in the wild and no public exploit code.

Affected product: Pidgin Pidgin. 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-2011-4939/ (Markdown: https://insights.sbomify.com/CVE-2011-4939/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-4939
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-4939
- OSV: https://osv.dev/vulnerability/CVE-2011-4939

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-4939/
Summaries are generated and may contain mistakes; the official description above is the record.