CVE-2026-39830

A flaw was found in golang.org/x/crypto/ssh. A remote malicious SSH peer can exploit this by sending unsolicited global request responses, which fills an internal buffer and blocks the connection's read loop. This prevents the associated resources from being released, leading to a resource leak per connection. The consequence is a Denial of Service (DoS) for the affected system.

This is an Important denial of service flaw in golang.org/x/crypto/ssh. A remote, unauthenticated attacker can exploit this vulnerability by sending unsolicited global request responses to an affected SSH server, leading to resource exhaustion and a denial of service. The impact is considered Important due to the potential for unauthenticated remote disruption of services utilizing the vulnerable SSH library.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this denial of service vulnerability, restrict network access to any service that utilizes the golang.org/x/crypto/ssh library and is exposed to untrusted networks. Implement firewall rules to allow connections only from trusted hosts or networks. This action limits the ability of malicious peers to send unsolicited global request responses. A restart of the affected service may be necessary for the new network rules to be applied effectively.