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CVE-2026-56855highCWE-770

Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.5epss 0.4%
exploitation probability
0.4%top 69% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H