{"id":"CVE-2026-97031","state":"PUBLISHED","title":"Reject malformed ECH outer extension references in crypto/tls","description":"Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result.","publishedAt":"2026-10-08T22:53:58.775Z","updatedAt":"2026-10-09T15:59:17.238Z","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":"1.26.9","versionType":"semver"},{"version":"1.27.0-0","status":"affected","lessThan":"1.27.2","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"decodeInnerClientHello"},{"name":"Conn.Handshake"},{"name":"Conn.HandshakeContext"},{"name":"Conn.Read"},{"name":"Conn.Write"},{"name":"Dial"},{"name":"DialWithDialer"},{"name":"Dialer.Dial"},{"name":"Dialer.DialContext"},{"name":"QUICConn.Start"}]}],"references":["https://go.dev/cl/847312","https://go.dev/issue/81855","https://groups.google.com/g/golang-announce/c/U2fTuyDJznI","https://pkg.go.dev/vuln/GO-2026-6607"],"weaknesses":["CWE-405"],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/97xxx/CVE-2026-97031.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-97031","state":"PUBLISHED","datePublished":"2026-10-08T22:53:58.775Z","dateUpdated":"2026-10-09T15:59:17.238Z","assignerShortName":"Go","assignerOrgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateReserved":"2026-09-23T23:03:36.988Z"},"containers":{"cna":{"title":"Reject malformed ECH outer extension references in crypto/tls","descriptions":[{"lang":"en","value":"Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references. We now reject these as malformed and curb the memory amplification vector as a result."}],"affected":[{"vendor":"Go standard library","product":"crypto/tls","packageName":"crypto/tls","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThan":"1.26.9","versionType":"semver"},{"version":"1.27.0-0","status":"affected","lessThan":"1.27.2","versionType":"semver"}],"collectionURL":"https://pkg.go.dev","programRoutines":[{"name":"decodeInnerClientHello"},{"name":"Conn.Handshake"},{"name":"Conn.HandshakeContext"},{"name":"Conn.Read"},{"name":"Conn.Write"},{"name":"Dial"},{"name":"DialWithDialer"},{"name":"Dialer.Dial"},{"name":"Dialer.DialContext"},{"name":"QUICConn.Start"}]}],"references":[{"url":"https://go.dev/cl/847312"},{"url":"https://go.dev/issue/81855"},{"url":"https://groups.google.com/g/golang-announce/c/U2fTuyDJznI"},{"url":"https://pkg.go.dev/vuln/GO-2026-6607"}],"problemTypes":[{"descriptions":[{"lang":"en","description":"CWE-405: Asymmetric Resource Consumption"}]}],"providerMetadata":{"shortName":"Go","orgId":"1bb62c36-49e3-4200-9d77-64a1400537cc","dateUpdated":"2026-10-08T22:53:58.775Z"}},"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":"2026-10-09T15:59:09.530145Z","id":"CVE-2026-97031","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-405","type":"CWE","lang":"en","description":"CWE-405 Asymmetric Resource Consumption (Amplification)"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-09T15:59:17.238Z"}}]}}}