# RUSTSEC-2026-0413: Use-after-free of caller-owned server name in client connection constructors


- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 26 Oct 2026
- **Also known as:** GHSA-rc3f-4j82-cmrg

## What is RUSTSEC-2026-0413?

RUSTSEC-2026-0413 is a vulnerability in rustls-ffi, published on 26 Oct 2026. 

### Official description

In rustls-ffi 0.12.0 through 0.15.6, `rustls_client_connection_new()` and
`rustls_client_connection_new_alpn()` retained a reference to the caller's
`server_name` buffer after returning, rather than copying it. The API
documentation did not require the buffer to outlive the call and as a result
if the caller freed or reused the buffer, later TLS processing read freed
memory.

Clients that free or reuse the `server_name` buffer after the constructor
returns are affected. This is most likely for language bindings that pass
temporary strings. Callers that keep the `server_name` buffer alive for the
lifetime of the `rustls_client_config` are not affected.

Versions 0.12.0 through 0.15.6 are affected. Version 0.15.7+ changed these APIs
to copy the input buffer.

## Which versions are affected by RUSTSEC-2026-0413?

1 open source package ship an affected version, including rustls-ffi.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rustls-ffi` | crates.io | From 0.12.0 | 0.15.7 |

## How do I fix RUSTSEC-2026-0413?

Upgrade rustls-ffi to 0.15.7 or later.

## Is RUSTSEC-2026-0413 being exploited?

There is no known exploitation of RUSTSEC-2026-0413 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0413 and fix it if it is affected.

What it is: RUSTSEC-2026-0413 is a vulnerability in rustls-ffi, published on 26 Oct 2026. 
Exploitation: There is no known exploitation of RUSTSEC-2026-0413 in the wild and no public exploit code.

Affected packages and fixed versions:
- rustls-ffi (crates.io): affected from 0.12.0; fixed in 0.15.7

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/RUSTSEC-2026-0413/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0413/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0413

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0413/
Summaries are generated and may contain mistakes; the official description above is the record.