# CVE-2011-2943: Null dereference in n/a

> Remote attackers can crash Pidgin via crafted IRC nicknames, requiring user interaction to trigger the denial of service.

- **Severity:** Medium 4.3 (`AV:N/AC:M/Au:N/C:N/I:N/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 29 Aug 2011
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2011-2943, GHSA-39wr-cgvv-f2w7

## What is CVE-2011-2943?

CVE-2011-2943 is a medium-severity vulnerability in Pidgin Pidgin, published on 29 Aug 2011. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

The irc_msg_who function in msgs.c in the IRC protocol plugin in libpurple 2.8.0 through 2.9.0 in Pidgin before 2.10.0 does not properly validate characters in nicknames, which allows user-assisted remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted nickname that is not properly handled in a WHO response.

## Which versions are affected by CVE-2011-2943?

It affects 2 products.


Products: Pidgin Libpurple, Pidgin Pidgin.

## How do I fix CVE-2011-2943?

Upgrade to a fixed version.

## Is CVE-2011-2943 being exploited?

There is no known exploitation of CVE-2011-2943 in the wild and no public exploit code.

## Other vulnerabilities in Pidgin Pidgin

- [CVE-2009-2703](https://insights.sbomify.com/CVE-2009-2703/): Null dereference in n/a (medium 5.0)
- [CVE-2009-3083](https://insights.sbomify.com/CVE-2009-3083/): Null dereference in n/a (medium 5.0)
- [CVE-2009-3084](https://insights.sbomify.com/CVE-2009-3084/): The msn_slp_process_msg function in libpurple/protocols/msn/slpcall.c in the MSN protocol plugin in libpurple 2.6.0 and 2.6.1, as used in Pi (medium 5.0)
- [CVE-2009-3085](https://insights.sbomify.com/CVE-2009-3085/): Denial of service in n/a (medium 5.0)
- [CVE-2011-3594](https://insights.sbomify.com/CVE-2011-3594/): Memory corruption in n/a (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2011-2943 and fix it if it is affected.

What it is: CVE-2011-2943 is a medium-severity vulnerability in Pidgin Pidgin, published on 29 Aug 2011. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2011-2943 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-2011-2943/ (Markdown: https://insights.sbomify.com/CVE-2011-2943/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2011-2943
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2011-2943
- OSV: https://osv.dev/vulnerability/CVE-2011-2943

---
From sbomify Insights: https://insights.sbomify.com/CVE-2011-2943/
Summaries are generated and may contain mistakes; the official description above is the record.