{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-123611", "assignerOrgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "state": "PUBLISHED", "assignerShortName": "VulnCheck", "dateReserved": "2026-11-06T01:02:39.794Z", "datePublished": "2026-11-08T01:38:36.176Z", "dateUpdated": "2026-11-08T01:38:36.176Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "83251b91-4cc7-4094-a5c7-464a1b83ea10", "shortName": "VulnCheck", "dateUpdated": "2026-11-08T01:38:36.176Z"}, "datePublic": "2026-10-14T00:00:00.000Z", "title": "rustls before 0.23.46 Key Exchange Downgrade via Unauthenticated ServerHello", "descriptions": [{"lang": "en", "value": "rustls before 0.23.46 contains a key exchange downgrade vulnerability that allows network attackers to poison the per-server-name key-exchange group record via an unauthenticated ServerHello. Attackers can answer one connection with a ServerHello selecting X25519, causing later ClientHellos to send only classical shares and lose post-quantum confidentiality."}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')", "cweId": "CWE-757", "type": "CWE"}]}], "affected": [{"vendor": "rustls", "product": "rustls", "defaultStatus": "unaffected", "packageURL": "pkg:cargo/rustls", "versions": [{"version": "0", "status": "affected", "versionType": "semver", "lessThan": "0.23.46"}, {"version": "0.23.46", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:rustls_project:rustls:*:*:*:*:*:*:*:*", "versionEndExcluding": "0.23.46"}]}]}], "metrics": [{"format": "CVSS", "cvssV4_0": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "attackRequirements": "PRESENT", "privilegesRequired": "NONE", "userInteraction": "NONE", "vulnConfidentialityImpact": "LOW", "vulnIntegrityImpact": "NONE", "vulnAvailabilityImpact": "NONE", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "baseScore": 6.3, "baseSeverity": "MEDIUM"}}, {"format": "CVSS", "cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N", "attackVector": "NETWORK", "attackComplexity": "HIGH", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE", "baseScore": 3.7, "baseSeverity": "LOW"}}], "references": [{"url": "https://github.com/rustls/rustls/security/advisories/GHSA-w44r-93j7-qv28", "tags": ["vendor-advisory"], "name": "GitHub Security Advisory (GHSA-w44r-93j7-qv28)"}, {"name": "VulnCheck Advisory: rustls before 0.23.46 Key Exchange Downgrade via Unauthenticated ServerHello", "tags": ["third-party-advisory"], "url": "https://www.vulncheck.com/advisories/rustls-before-0.23.46-key-exchange-downgrade-via-unauthenticated-serverhello"}], "credits": [{"lang": "en", "value": "Adam010341", "type": "reporter"}], "x_generator": {"engine": "vulncheck-endgame"}}}}