{"id":"CVE-2026-56862","state":"PUBLISHED","title":"Limit handshake messages we are willing to accept post-handshake in crypto/tls","description":"Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely.","publishedAt":"2026-08-13T21:58:53.216Z","updatedAt":"2026-08-14T15:29:41.741Z","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":["Go standard library crypto/tls"],"affected":[{"vendor":"Go standard library","product":"crypto/tls","packageName":"crypto/tls","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"1.25.13","versionType":"semver"},{"version":"1.26.0-0","status":"affected","lessThan":"1.26.6","versionType":"semver"},{"version":"1.27.0-0","status":"affected","lessThan":"1.27.0-rc.3","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"Conn.readRecordOrCCS"},{"name":"Conn.Handshake"},{"name":"Conn.HandshakeContext"},{"name":"Conn.Read"},{"name":"Conn.Write"},{"name":"Dial"},{"name":"DialWithDialer"},{"name":"Dialer.Dial"},{"name":"Dialer.DialContext"},{"name":"QUICConn.HandleData"},{"name":"QUICConn.Start"}]}],"references":["https://go.dev/issue/80528","https://go.dev/cl/804261","https://groups.google.com/g/golang-announce/c/94pEornpRlI","https://pkg.go.dev/vuln/GO-2026-6090"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/56xxx/CVE-2026-56862.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-56862","state":"PUBLISHED","datePublished":"2026-08-13T21:58:53.216Z","dateUpdated":"2026-08-14T15:29:41.741Z","assignerShortName":"Go","assignerOrgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateReserved":"2026-06-23T15:10:49.353Z"},"containers":{"cna":{"title":"Limit handshake messages we are willing to accept post-handshake in crypto/tls","descriptions":[{"lang":"en","value":"Handshake messages, such as KeyUpdate, are always considered as state-advancing, regardless of whether a handshake has been completed or not. As a result, a malicious client can keep sending KeyUpdate messages to force the server to keep performing key derivation operations indefinitely."}],"affected":[{"vendor":"Go standard library","product":"crypto/tls","packageName":"crypto/tls","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"1.25.13","versionType":"semver"},{"version":"1.26.0-0","status":"affected","lessThan":"1.26.6","versionType":"semver"},{"version":"1.27.0-0","status":"affected","lessThan":"1.27.0-rc.3","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"Conn.readRecordOrCCS"},{"name":"Conn.Handshake"},{"name":"Conn.HandshakeContext"},{"name":"Conn.Read"},{"name":"Conn.Write"},{"name":"Dial"},{"name":"DialWithDialer"},{"name":"Dialer.Dial"},{"name":"Dialer.DialContext"},{"name":"QUICConn.HandleData"},{"name":"QUICConn.Start"}]}],"references":[{"url":"https://go.dev/issue/80528"},{"url":"https://go.dev/cl/804261"},{"url":"https://groups.google.com/g/golang-announce/c/94pEornpRlI"},{"url":"https://pkg.go.dev/vuln/GO-2026-6090"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling"}]}],"providerMetadata":{"shortName":"Go","orgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateUpdated":"2026-08-13T21:58:53.216Z"},"credits":[{"lang":"en","value":"Qi Deng of Aurascape.ai"}]},"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":"2026-08-14T15:27:34.651997Z","id":"CVE-2026-56862","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":"2026-08-14T15:29:41.741Z"}}]}}}