CVE-2026-39827 Invoking memory leak when rejecting channels can lead to DoS in golang.org/x/crypto/ssh

Medium 6.5 Published 22 May 2026 Updated 22 May 2026

An authenticated SSH client can crash the server by repeatedly opening rejected channels, causing unbounded memory growth and service disruption.

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

What is CVE-2026-39827?

CVE-2026-39827 is a medium-severity denial of service vulnerability in golang.org/x/crypto/ssh, published on 22 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

An authenticated SSH client that repeatedly opened channels which were rejected by the server caused unbounded memory growth, eventually crashing the server process and affecting all connected users. Rejected channels are now properly removed from the connection's internal state and released for garbage collection.

Weakness: CWE-924

Which versions are affected by CVE-2026-39827?

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-2026-39827?

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

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-39827 being exploited?

There is no known exploitation of CVE-2026-39827 in the wild and no public exploit code.

Sources

Also known as AZL-87170, AZL-87260, AZL-87293, AZL-87411, AZL-87474, AZL-87636 and 1108 more.