# Use-after-free of caller-owned server name in client connection constructors

Advisory record · `GHSA-rc3f-4j82-cmrg`

- **Identifiers:** `GHSA-rc3f-4j82-cmrg` · `RUSTSEC-2026-0413`
- **State:** Confirmed
- **Severity:** No CVSS score
- **Critical:** No
- **Published:** 26 Oct 2026
- **Updated:** 27 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 26 Oct 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `rustls-ffi` (crates.io): affected `>=0.12.0, <0.15.7`; fixed in `0.15.7`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> rustls-ffi versions 0.12.0 through 0.15.6 are vulnerable. In these versions, the client connection constructors rustls_client_connection_new() and rustls_client_connection_new_alpn() keep a reference to the caller's server_name buffer instead of copying it. If the caller frees or reuses that buffer after the call returns, later TLS processing can read freed memory. Upgrade to version 0.15.7 or later, which copies the input buffer. Until then, keep the server_name buffer alive for the lifetime of the rustls_client_config.

Written 3 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

No source has published a CVSS score for this record yet.

- **CISA KEV:** Not listed.
- **EPSS:** No score.

## Timeline

- 31 Oct 2026, 14:24 UTC: First seen by agentprime
- 31 Oct 2026, 14:24 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/RUSTSEC-2026-0413)

## Sources

- [GitHub Advisory Database: GHSA-rc3f-4j82-cmrg](https://github.com/advisories/GHSA-rc3f-4j82-cmrg)
- [OSV: GHSA-rc3f-4j82-cmrg](https://osv.dev/vulnerability/GHSA-rc3f-4j82-cmrg)
- <https://crates.io/crates/rustls-ffi>
- <https://rustsec.org/advisories/RUSTSEC-2026-0413.html>
- <https://github.com/rustls/rustls-ffi/releases/tag/v/0.15.7>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-rc3f-4j82-cmrg>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-rc3f-4j82-cmrg/>. Everything for agents: <https://agentprime.io/llms.txt>.