CVE-2026-59843: Libssh

Medium severity, CVSS 6.5. EPSS: 0.7% chance of exploitation in the next 30 days.

A flaw was found in libssh. A remote authenticated peer can advertise a zero maximum packet size in SSH_MSG_CHANNEL_OPEN, causing later channel writes to loop indefinitely and consume CPU, leading to denial of service.

Affected products

• Libssh Libssh: affected versions not specified
• Red Hat Enterprise Linux: version 8.0 only; version 9.0 only; version 10.0 only
• Red Hat Hardened Images: affected versions not specified

Published 2026-07-21. Last modified 2026-09-01.