{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-63576","assignerOrgId":"91579145-5d7b-4cc5-b925-a0262ff19630","state":"PUBLISHED","assignerShortName":"bcorg","dateReserved":"2026-07-16T23:51:51.306Z","datePublished":"2026-10-02T07:07:02.513Z","dateUpdated":"2026-10-06T19:31:40.267Z"},"containers":{"cna":{"providerMetadata":{"orgId":"91579145-5d7b-4cc5-b925-a0262ff19630","shortName":"bcorg","dateUpdated":"2026-10-02T07:07:02.513Z"},"title":"URI name constraints checked against a mis-parsed host","problemTypes":[{"descriptions":[{"lang":"en","cweId":"CWE-295","description":"CWE-295 Improper Certificate Validation","type":"CWE"}]}],"impacts":[{"descriptions":[{"lang":"en","value":"Integrity (bypass of permitted/excluded URI name constraints in certification path validation)"}]}],"affected":[{"vendor":"Legion of the Bouncy Castle Inc.","product":"bc-csharp","collectionURL":"https://www.nuget.org/packages/BouncyCastle.Cryptography","packageName":"BouncyCastle.Cryptography","repo":"https://github.com/bcgit/bc-csharp","programFiles":["crypto/src/pkix/PkixNameConstraintValidator.cs","crypto/src/pkix/NameConstraintUtilities.cs","crypto/src/pkix/NameConstraintUri.cs"],"versions":[{"status":"affected","version":"0","lessThan":"2.7.0","versionType":"semver"}],"defaultStatus":"unaffected"}],"descriptions":[{"lang":"en","value":"Improper certificate validation in PkixNameConstraintValidator (ExtractHostFromURL) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a name-constrained subordinate CA, or anyone able to obtain certificates with chosen subjectAltName URIs from such a CA, to bypass permitted or excluded uniformResourceIdentifier name constraints during certification path validation via a URI whose path, query, fragment or userinfo contains characters such as '@' or ':', because the host was extracted by string slicing without first isolating the RFC 3986 authority component, so the host compared against the constraints could differ from the URI's actual host.","supportingMedia":[{"type":"text/html","base64":false,"value":"Improper certificate validation in PkixNameConstraintValidator (ExtractHostFromURL) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a name-constrained subordinate CA, or anyone able to obtain certificates with chosen subjectAltName URIs from such a CA, to bypass permitted or excluded uniformResourceIdentifier name constraints during certification path validation via a URI whose path, query, fragment or userinfo contains characters such as '@' or ':', because the host was extracted by string slicing without first isolating the RFC 3986 authority component, so the host compared against the constraints could differ from the URI's actual host."}]}],"references":[{"url":"https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63576","tags":["vendor-advisory"]},{"url":"https://github.com/bcgit/bc-csharp/commit/f196a22bbf7765cc19b0c4f4645c74ea7ad35e09","tags":["patch"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"HIGH","baseScore":8.2,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}}],"credits":[{"lang":"en","value":"Discovered by Claude, Anthropic's AI assistant, and triaged by the Anthropic security team in collaboration with Anthropic Research.","type":"finder"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Claude Opus 5.5"},"x_antReportIds":["ANT-2026-R05HVR25"]},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-06T19:21:06.114263Z","id":"CVE-2026-63576","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-10-06T19:31:40.267Z"}}]}}