CVE-2026-42508 Invoking auth bypass via unenforced @revoked status in golang.org/x/crypto/ssh/knownhosts

Critical 9.1 Published 22 May 2026 Updated 15 Sep 2026

Attackers can bypass SSH host key revocation checks in the Go crypto library, allowing connections to revoked hosts.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-42508?

CVE-2026-42508 is a critical authentication bypass vulnerability in golang.org/x/crypto/ssh/knownhosts, published on 22 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Previously, a revoked 'SignatureKey' belonging to a CA was not correctly checked for revocation. Now, both the 'key' and 'key.SignatureKey' are checked for @revoked.

Weakness: CWE-295

Which versions are affected by CVE-2026-42508?

3 open source packages ship an affected version, including golang.org/x/crypto. It affects 1 product.

Package	Affected	Fixed in
`golang.org/x/crypto` Go	All versions	`0.52.0`
`golang.org/x/crypto` Go	All versions	`0.52.0`
`golang.org/x/crypto` Go	All versions	`0.52.0`

Products include Golang Crypto.

How do I fix CVE-2026-42508?

Upgrade golang.org/x/crypto to 0.52.0 or later.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-42508 being exploited?

There is no known exploitation of CVE-2026-42508 in the wild and no public exploit code.

Sources

Also known as AZL-87224, AZL-87284, AZL-88188, AZL-88359, BELL-CVE-2026-42508, CLEANSTART-2026-AH42330 and 1111 more.