---
title: "CVE-2026-39832: golang.org/x/crypto doesn't drop invoking agent constraints when forwarding keys"
url: https://erroneo.us/security/cve/CVE-2026-39832/
description: "CVE-2026-39832 (golang.org/x/crypto (Go)): When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-05-22
date_modified: 2026-09-15
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-39832"
kev: false
cvss: 8.7
epss: 0.00716
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-39832: golang.org/x/crypto doesn't drop invoking agent constraints when forwarding keys

**Signal:** Normal patch cycle. No exploitation signal; fix it in your next routine update if you are affected. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.7% , percentile 53: FIRST’s model estimates a 0.7% chance of exploitation activity in the next 30 days, higher than 53% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes golang.org/x/crypto (Go) < 0.52.0, fixed in 0.52.0 . Check your lockfile, including transitive dependencies.

## What it is

When adding a key to a remote agent constraint extensions such as restrict-destination-v00@openssh.com were not serialized in the request. Destination restrictions were silently stripped when forwarding keys, allowing unrestricted use of the key on the remote host. The client now serializes all constraint extensions. Additionally, the in-memory keyring returned by NewKeyring() now rejects keys with unsupported constraint extensions instead of silently ignoring them.

## Affected packages

- Go `golang.org/x/crypto` < 0.52.0 → fixed: 0.52.0

## Affected products (CVE record)

- golang.org/x/crypto golang.org/x/crypto/ssh/agent: < 0.52.0

## Severity

- CISA-ADP CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`
- redhat-SADP CVSS 3.1: 8.7 `CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`
- GitHub CVSS 3.1: 9.1 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.72% probability of exploitation activity in the next 30 days; percentile 53.

## Sources

- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:41019)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36796)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36199)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37072)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:35833)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:49944)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:67450)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37410)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37123)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:61314)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:66521)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:43692)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36319)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36625)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36651)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:40945)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:40118)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36648)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:41036)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:52857)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:52910)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37387)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:41031)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:42146)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:43052)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:42796)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:41066)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:40262)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:40972)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:36797)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:37271)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:57194)
- [access.redhat.com](https://access.redhat.com/errata/RHSA-2026:59579)
- [GitHub Advisory GHSA-f5wc-c3c7-36mc](https://github.com/advisories/GHSA-f5wc-c3c7-36mc)
- [CVE.org record CVE-2026-39832](https://www.cve.org/CVERecord?id=CVE-2026-39832)
- [NVD entry CVE-2026-39832](https://nvd.nist.gov/vuln/detail/CVE-2026-39832)
- [go.dev](https://go.dev/issue/79435)
- [go.dev](https://go.dev/cl/778640)
- [go.dev](https://go.dev/cl/778641)
- [groups.google.com](https://groups.google.com/g/golang-announce/c/a082jnz-LvI)
- [pkg.go.dev](https://pkg.go.dev/vuln/GO-2026-5006)
- [access.redhat.com](https://access.redhat.com/security/cve/CVE-2026-39832)
- [RHBZ#2480685](https://bugzilla.redhat.com/show_bug.cgi?id=2480685)
- [security.access.redhat.com](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-39832.json)
- [go.dev](https://go.dev/cl/778642)

---
Source page: https://erroneo.us/security/cve/CVE-2026-39832/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt