# CVE-2021-3738: Use after free in samba

> A use-after-free in Samba's DCE/RPC association groups can cause crashes or potentially allow privilege escalation by pointing to invalid session data.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 2 Mar 2022
- **Updated:** 3 Aug 2024
- **Also known as:** ALPINE-CVE-2021-3738, AZL-37005, AZL-8905, CLSA-2025-1760370936, CLSA-2025-1765285897, DEBIAN-CVE-2021-3738, ECHO-b5d2-47be-37f6, GHSA-jrfc-f73c-qmrr, UBUNTU-CVE-2021-3738

## What is CVE-2021-3738?

CVE-2021-3738 is a high-severity use after free vulnerability in Samba Samba, published on 2 Mar 2022. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections via a mechanism called 'association groups'. These handles can reference connections to our sam.ldb database. However while the database was correctly shared, the user credentials state was only pointed at, and when one connection within that association group ended, the database would be left pointing at an invalid 'struct session_info'. The most likely outcome here is a crash, but it is possible that the use-after-free could instead allow different user state to be pointed at and this might allow more privileged access.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2021-3738?

It affects 1 product.


Products: Samba Samba.

## How do I fix CVE-2021-3738?

Apply the vendor's patch.

## Is CVE-2021-3738 being exploited?

There is no known exploitation of CVE-2021-3738 in the wild and no public exploit code.

## Other vulnerabilities in Samba Samba

- [CVE-2012-1182](https://insights.sbomify.com/CVE-2012-1182/): Integer overflow in n/a (critical 10.0)
- [CVE-2007-2446](https://insights.sbomify.com/CVE-2007-2446/): Memory corruption in n/a (critical 10.0)
- [CVE-2004-0600](https://insights.sbomify.com/CVE-2004-0600/): Memory corruption in n/a (critical 10.0)
- [CVE-1999-0810](https://insights.sbomify.com/CVE-1999-0810/): Denial of service in n/a (critical 10.0)
- [CVE-1999-0182](https://insights.sbomify.com/CVE-1999-0182/): Memory corruption in n/a (critical 10.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-3738 and fix it if it is affected.

What it is: CVE-2021-3738 is a high-severity use after free vulnerability in Samba Samba, published on 2 Mar 2022. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-3738 in the wild and no public exploit code.

Affected product: Samba Samba. 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-2021-3738/ (Markdown: https://insights.sbomify.com/CVE-2021-3738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3738
- OSV: https://osv.dev/vulnerability/CVE-2021-3738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3738/
Summaries are generated and may contain mistakes; the official description above is the record.