{"id":"CVE-2026-56855","state":"PUBLISHED","title":"Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh","description":"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.","publishedAt":"2026-09-02T19:37:05.807Z","updatedAt":"2026-09-03T14:14:40.169Z","severity":{"score":7.5,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"Go","products":["golang.org/x/crypto golang.org/x/crypto/ssh"],"affected":[{"vendor":"golang.org/x/crypto","product":"golang.org/x/crypto/ssh","packageName":"golang.org/x/crypto/ssh","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.56.0","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"channel.handlePacket"},{"name":"Dial"},{"name":"NewClientConn"},{"name":"NewControlClientConn"},{"name":"NewServerConn"}]}],"references":["https://go.dev/issue/81317","https://go.dev/cl/826524","https://groups.google.com/g/golang-announce/c/1y3fb2np35U","https://pkg.go.dev/vuln/GO-2026-6355"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/56xxx/CVE-2026-56855.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-56855","state":"PUBLISHED","datePublished":"2026-09-02T19:37:05.807Z","dateUpdated":"2026-09-03T14:14:40.169Z","assignerShortName":"Go","assignerOrgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateReserved":"2026-06-23T15:10:49.353Z"},"containers":{"cna":{"title":"Prevent DoS on deadlocked established channel in golang.org/x/crypto/ssh","descriptions":[{"lang":"en","value":"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":[{"vendor":"golang.org/x/crypto","product":"golang.org/x/crypto/ssh","packageName":"golang.org/x/crypto/ssh","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"0.56.0","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"channel.handlePacket"},{"name":"Dial"},{"name":"NewClientConn"},{"name":"NewControlClientConn"},{"name":"NewServerConn"}]}],"references":[{"url":"https://go.dev/issue/81317"},{"url":"https://go.dev/cl/826524"},{"url":"https://groups.google.com/g/golang-announce/c/1y3fb2np35U"},{"url":"https://pkg.go.dev/vuln/GO-2026-6355"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling"}]}],"providerMetadata":{"shortName":"Go","orgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateUpdated":"2026-09-02T19:37:05.807Z"},"credits":[{"lang":"en","value":"Will Mortensen"}]},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":7.5,"attackVector":"NETWORK","baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"NONE","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"timestamp":"2026-09-03T14:13:54.397574Z","id":"CVE-2026-56855","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","type":"CWE","lang":"en","description":"CWE-770 Allocation of Resources Without Limits or Throttling"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-03T14:14:40.169Z"}}]}}}