# GHSA-rp9h-rf7g-hwgr: s2n-tls has undefined behavior at process exit

> A race condition in s2n-tls cleanup handlers can cause segmentation faults during process exit in multi-threaded environments.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 14 Nov 2024

## What is GHSA-rp9h-rf7g-hwgr?

GHSA-rp9h-rf7g-hwgr is a vulnerability in s2n-tls, published on 14 Nov 2024. 

### Official description

### Impact
s2n-tls uses the Linux atexit function to register functions that clean up the global state when the process exits. In multi-threaded environments, the atexit handler may clean up state which is still in use by other threads. When this occurs, the exiting process may experience a segmentation fault or other undefined behavior. 

Customers of AWS services do not need to take action. Applications using s2n-tls should upgrade to the most recent release of s2n-tls.

**Impacted versions**: < v1.5.9.

### Patches
The patch commit [493b771](https://github.com/aws/s2n-tls/commit/493b77167dc367c394de23cfe78a029298e2a254) is included in s2n-tls v1.5.9 [1]

### Workarounds
The atexit handler may be disabled by calling `s2n_disable_atexit()` prior to initializing s2n-tls. The atexit handler is off by default in the patched versions. For further details, refer to [s2n-tls Usage Guide: Initialization and Teardown](https://github.com/aws/s2n-tls/blob/main/docs/usage-guide/topics/ch02-initialization.md).

If you have any questions or comments about this advisory, we ask that you contact AWS/Amazon Security via our vulnerability reporting page [2] or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.

[1] https://github.com/aws/s2n-tls/releases/tag/v1.5.9
[2] Vulnerability reporting page: https://aws.amazon.com/security/vulnerability-reporting

## Which versions are affected by GHSA-rp9h-rf7g-hwgr?

2 open source packages ship an affected version, including s2n-tls.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `s2n-tls` | crates.io | All versions | 0.3.7 |
| `s2n-tls` | crates.io | All versions | 0.3.7 |

## How do I fix GHSA-rp9h-rf7g-hwgr?

Upgrade s2n-tls to 0.3.7 or later.

## Is GHSA-rp9h-rf7g-hwgr being exploited?

There is no known exploitation of GHSA-rp9h-rf7g-hwgr in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for GHSA-rp9h-rf7g-hwgr and fix it if it is affected.

What it is: GHSA-rp9h-rf7g-hwgr is a vulnerability in s2n-tls, published on 14 Nov 2024. 
Exploitation: There is no known exploitation of GHSA-rp9h-rf7g-hwgr in the wild and no public exploit code.

Affected packages and fixed versions:
- s2n-tls (crates.io): affected all versions; fixed in 0.3.7
- s2n-tls (crates.io): affected all versions; fixed in 0.3.7

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/GHSA-rp9h-rf7g-hwgr/ (Markdown: https://insights.sbomify.com/GHSA-rp9h-rf7g-hwgr/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/GHSA-rp9h-rf7g-hwgr

---
From sbomify Insights: https://insights.sbomify.com/GHSA-rp9h-rf7g-hwgr/
Summaries are generated and may contain mistakes; the official description above is the record.