Critical· 9.1

CVE-2026-39832

A critical flaw in Go’s crypto library lets attackers bypass destination restrictions on SSH keys when they are forwarded, allowing the key to be used on any remote host. The problem occurs because constraint extensions were not serialized, so they were silently removed. The library now serializes all extensions and rejects unsupported ones.

publishedMay 22, 2026

last modifiedAug 4, 2026

sourcesNVD

severity · cvss

9.1

critical · how bad it is

exploitation · epss

<1%

45th percentile · chance of exploitation in 30 days

(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →

auto-deletes from the system

counting…on Sep 1, 2026

No official fix yet. If none appears within 45 days of first tracking, this entry is removed automatically.

Who is affected

Go crypto library (golang crypto) used by developers for SSH key management.

Real-world impact

An attacker could use a forwarded SSH key without restrictions, potentially gaining unauthorized access to remote systems.

Why this severity

The CVSS score of 9.1 reflects the high impact of confidentiality and integrity loss with no authentication or user interaction required, making it a critical vulnerability.

What to do about it

no official fix yet

No official fix or mitigation is documented in the sources yet. Monitor the vendor advisory and apply the patch as soon as it is released.

No fix documented in sources

Timeline

May 22, 2026 · May 22, 2026
Published
Disclosed and added to the National Vulnerability Database.
Aug 4, 2026 · 7h ago
Advisory updated
The NVD record was last revised.

How it’s attacked

Attack vectorNetwork (remote)

Attack complexityLow

Privileges requiredNone

User interactionNone needed

ScopeUnchanged

Confidentiality impactHigh

Integrity impactHigh

Availability impactNone

References & advisories

NVD advisory ↗Search advisories ↗

(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →