{"id":"CVE-2026-42505","sourceIdentifier":"security@golang.org","published":"2026-07-08T17:17:21.497","lastModified":"2026-10-25T17:10:00.197","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello."},{"lang":"es","value":"Negociaciones de enlace que usaron Saludo de Cliente Cifrado podrían ser desanonimizadas por un observador de red pasivo debido a una divulgación de identidades de clave precompartida en el saludo de cliente sin cifrar."}],"affected":[{"source":"security@golang.org","affectedData":[{"vendor":"Go standard library","product":"crypto/tls","defaultStatus":"unaffected","collectionURL":"https://pkg.go.dev","packageName":"crypto/tls","programRoutines":[{"name":"clientHelloMsg.marshalMsg"},{"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.SendSessionTicket"},{"name":"QUICConn.Start"}],"versions":[{"version":"0","lessThan":"1.25.12","versionType":"semver","status":"affected"},{"version":"1.26.0-0","lessThan":"1.26.5","versionType":"semver","status":"affected"},{"version":"1.27.0-0","lessThan":"1.27.0-rc.2","versionType":"semver","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","baseScore":5.3,"baseSeverity":"MEDIUM","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"LOW","integrityImpact":"NONE","availabilityImpact":"NONE"},"exploitabilityScore":3.9,"impactScore":1.4}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-07-08T18:03:53.821942Z","id":"CVE-2026-42505","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","description":[{"lang":"en","value":"CWE-201"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*","versionStartIncluding":"1.23.0","versionEndExcluding":"1.25.12","matchCriteriaId":"B302AE7B-BC6D-484F-912F-711617651A1A"},{"vulnerable":true,"criteria":"cpe:2.3:a:golang:go:*:*:*:*:*:*:*:*","versionStartIncluding":"1.26.0","versionEndExcluding":"1.26.5","matchCriteriaId":"08CDCAED-0C22-42D9-97A8-77F19DEECDB2"},{"vulnerable":true,"criteria":"cpe:2.3:a:golang:go:1.27:rc1:*:*:*:*:*:*","matchCriteriaId":"1062DCC7-46FE-4CF5-ADEF-BEC03F8AB39E"}]}]}],"references":[{"url":"https://go.dev/cl/775960","source":"security@golang.org","tags":["Patch"]},{"url":"https://go.dev/issue/79282","source":"security@golang.org","tags":["Issue Tracking","Patch"]},{"url":"https://groups.google.com/g/golang-announce/c/OrmQE_Yp5Sc","source":"security@golang.org","tags":["Mailing List","Release Notes","Vendor Advisory"]},{"url":"https://pkg.go.dev/vuln/GO-2026-5856","source":"security@golang.org","tags":["Vendor Advisory"]}]}