# Invoking agent constraints dropped when forwarding keys in golang.org/x/crypto/ssh/agent

Advisory record · `GHSA-f5wc-c3c7-36mc`

- **Identifiers:** `GHSA-f5wc-c3c7-36mc` · `CVE-2026-39832` · `GO-2026-5006`
- **State:** Confirmed
- **Severity:** CVSS 9.1 Critical
- **Critical:** Yes: CVSS 9+
- **Weakness (CWE):** [CWE-281](https://cwe.mitre.org/data/definitions/281.html)
- **Tags:** [CWE-281](https://agentprime.io/advisories/tag/cwe-281.md)
- **Published:** 22 May 2026
- **Updated:** 15 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 22 May 2026, 02:08 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Critical

Critical, because:

- CVSS score 9.1: 9.0 or more.

How we decide what’s critical: <https://agentprime.io/advisories/critical.md>

## Affected packages

- `golang.org/x/crypto` (Go): affected `<0.52.0`; fixed in `0.52.0`

## Machine-written summary

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

> Affected: golang.org/x/crypto versions before 0.52.0. When keys were added to a remote agent, constraint extensions such as restrict-destination-v00\@openssh.com were not sent, so destination restrictions were silently dropped when forwarding keys. This could let a key be used without its intended limits on the remote host. Upgrade to golang.org/x/crypto 0.52.0 or later, which serializes all constraint extensions and makes the in-memory keyring reject unsupported ones.

Written 1 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

- 9.1 Critical, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`, from ADP (CISA-ADP)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0068, the 52nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:13 UTC: First seen by agentprime
- 31 Oct 2026, 14:13 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GO-2026-5006)

## Sources

- [GitHub Advisory Database: GHSA-f5wc-c3c7-36mc](https://github.com/advisories/GHSA-f5wc-c3c7-36mc)
- [OSV: GHSA-f5wc-c3c7-36mc](https://osv.dev/vulnerability/GHSA-f5wc-c3c7-36mc)
- <https://go.dev/cl/778640>
- <https://go.dev/cl/778641>
- <https://groups.google.com/g/golang-announce/c/a082jnz-LvI>

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-f5wc-c3c7-36mc>, 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-f5wc-c3c7-36mc/>. Everything for agents: <https://agentprime.io/llms.txt>.