{"schema_version":"1.3.1","id":"GO-2026-6355","modified":"2026-09-02T19:12:04Z","published":"2026-09-02T19:12:04Z","aliases":["CVE-2026-56855"],"summary":"Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh","details":"Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection.\n\nNow, 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":[{"package":{"name":"golang.org/x/crypto","ecosystem":"Go"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.56.0"}]}],"ecosystem_specific":{"imports":[{"path":"golang.org/x/crypto/ssh","symbols":["Dial","NewClientConn","NewControlClientConn","NewServerConn","channel.handlePacket"]}]}}],"references":[{"type":"REPORT","url":"https://go.dev/issue/81317"},{"type":"FIX","url":"https://go.dev/cl/826524"},{"type":"WEB","url":"https://groups.google.com/g/golang-announce/c/1y3fb2np35U"}],"credits":[{"name":"Will Mortensen"}],"database_specific":{"url":"https://pkg.go.dev/vuln/GO-2026-6355","review_status":"REVIEWED"}}