# CVE-2009-3624: Use after free in n/a

> Local attackers can exploit a reference counting error in the Linux kernel keyring subsystem to escalate privileges or cause a system crash.

- **Severity:** Medium 4.6 (`AV:L/AC:L/Au:N/C:P/I:P/A:P`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 2 Nov 2009
- **Updated:** 7 Aug 2024
- **Also known as:** GHSA-gx7p-6h8g-757g

## What is CVE-2009-3624?

CVE-2009-3624 is a medium-severity use after free vulnerability in Linux kernel, published on 2 Nov 2009. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The get_instantiation_keyring function in security/keys/keyctl.c in the KEYS subsystem in the Linux kernel before 2.6.32-rc5 does not properly maintain the reference count of a keyring, which allows local users to gain privileges or cause a denial of service (OOPS) via vectors involving calls to this function without specifying a keyring by ID, as demonstrated by a series of keyctl request2 and keyctl list commands.

Weakness: CWE-310

## Which versions are affected by CVE-2009-3624?

It affects 2 products.


Products: Linux Kernel, Linux kernel.

## How do I fix CVE-2009-3624?

No fix has been published for CVE-2009-3624 yet. Limit exposure of the affected software until one is available.

## Is CVE-2009-3624 being exploited?

There is no known exploitation of CVE-2009-3624 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2009-2844](https://insights.sbomify.com/CVE-2009-2844/): Null dereference in n/a (high 7.8)
- [CVE-2009-1389](https://insights.sbomify.com/CVE-2009-1389/): Memory corruption in n/a (high 7.8)
- [CVE-2009-2767](https://insights.sbomify.com/CVE-2009-2767/): Null dereference in n/a (high 7.2)
- [CVE-2009-2406](https://insights.sbomify.com/CVE-2009-2406/): Memory corruption in n/a (medium 6.9)
- [CVE-2010-0309](https://insights.sbomify.com/CVE-2010-0309/): Denial of service in n/a (medium 6.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2009-3624 and fix it if it is affected.

What it is: CVE-2009-3624 is a medium-severity use after free vulnerability in Linux kernel, published on 2 Nov 2009. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2009-3624 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2009-3624/ (Markdown: https://insights.sbomify.com/CVE-2009-3624/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2009-3624
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2009-3624
- OSV: https://osv.dev/vulnerability/CVE-2009-3624

---
From sbomify Insights: https://insights.sbomify.com/CVE-2009-3624/
Summaries are generated and may contain mistakes; the official description above is the record.