CVE-2026-56855: Golang Crypto

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking.

Affected products

• Golang Crypto: before 0.56.0 (fixed in 0.56.0)

Published 2026-09-02. Last modified 2026-09-04.