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Not in CISA KEV
CRITICAL severity

CVE-2026-39832 — x/crypto

CRITICAL

CVE-2026-39832 is a critical-severity (CVSS 9.1) Deserialization of Untrusted Data vulnerability in golang.org/x/crypto. A fix is available for golang.org/x/crypto — see the affected versions and patch details below.

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

Also known asGHSA-f5wc-c3c7-36mcGO-2026-5006
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-39832.

EPSS Exploitation Probability

via FIRST.org ↗
0.7%probability of exploitation in next 30 days
Lower Risk-0.03%
Lower risk than most CVEs52th percentile — riskier than 52% of all scored CVEsHighest risk
0.00%0.41%0.81%1.22%0.1%0.7%Jun 26Sep 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-39832 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐹golang.org/x/crypto

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

When adding a key to a remote agent constraint extensions such as [email protected] 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

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogolang.org/x/cryptoall versions0.52.0go get golang.org/x/crypto@v0.52.0

Affected Products

1 product · 1 configurations
Application
cryptogolang
< 0.52.0
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for golang.org/x/crypto, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update golang.org/x/crypto to 0.52.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-39832 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant

This Important vulnerability in `golang.org/x/crypto/ssh/agent` allows for a security bypass when SSH keys with destination restrictions are forwarded via an SSH agent. This flaw could lead to unintended exposure of SSH keys, enabling an attacker to use the forwarded key without the specified restrictions on remote…

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
Source: Red Hat security advisory for CVE-2026-39832 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Enterprise Linux 10buildah-2:1.43.1-3.el10_2RHSA-2026:36199
Red Hat Enterprise Linux 10podman-7:5.8.2-4.el10_2RHSA-2026:37072
Red Hat Enterprise Linux 8container-tools:rhel8-8100020260701102925.afee755dRHSA-2026:35833
Red Hat Enterprise Linux 8.8 Telecommunications Update Servicecontainer-tools:rhel8-8080020260721142025.63b34585RHSA-2026:49944
Red Hat Enterprise Linux 9podman-6:5.8.2-4.el9_8RHSA-2026:37123
Red Hat Enterprise Linux 9buildah-2:1.43.1-3.el9_8RHSA-2026:37410
Red Hat Enterprise Linux 9.6 Extended Update Supportpodman-5:5.4.0-22.el9_6.5RHSA-2026:67450
RHEM 1.0 for RHEL 9flightctl-0:1.0.3-1.el9emRHSA-2026:36796

Frequently Asked Questions

When adding a key to a remote agent constraint extensions such as [email protected] 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.
O3 Security · Impact-Aware SCA

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CVE-2026-39832: x/crypto — Fixed in 0.52.0