{"id":"CVE-2026-63566","revision":null,"records":[{"revision":"ff80fc2cf5d9447da540b66a9f95fe10","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-63566","aliases":[],"title":"DTLS handshake reassembler allocates buffer from unchecked 24-bit length","description":"Memory allocation with excessive size value in the DTLS handshake reassembly (DtlsReliableHandshake, DtlsReassembler) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated DTLS peer to cause a denial of service through memory exhaustion via crafted handshake message fragments, because the reassembly buffer for each incoming handshake message was allocated at the 24-bit length declared in the fragment header, without the check against the peer's maximum handshake message size that TLS already applied. A fragment carrying no payload can force an allocation of almost 16 MB, for each of up to 16 pending messages per handshake, before the handshake is authenticated. DTLS servers and DTLS clients are both affected; TLS is not.","state":0,"publishedAt":"2026-10-02T06:57:21.718+00:00","modifiedAt":"2026-10-02T18:08:57.485+00:00","affected":[{"ecosystem":"https://www.nuget.org/packages/BouncyCastle.Cryptography","name":"BouncyCastle.Cryptography","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Legion of the Bouncy Castle Inc.\",\n                    \"product\": \"bc-csharp\",\n                    \"collectionURL\": \"https://www.nuget.org/packages/BouncyCastle.Cryptography\",\n                    \"packageName\": \"BouncyCastle.Cryptography\",\n                    \"repo\": \"https://github.com/bcgit/bc-csharp\",\n                    \"programFiles\": [\n                        \"crypto/src/tls/DtlsReliableHandshake.cs\",\n                        \"crypto/src/tls/DtlsReassembler.cs\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0\",\n                            \"lessThan\": \"2.7.0\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"defaultStatus\": \"unaffected\"\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","score":8.7,"severity":"HIGH"}],"references":["https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63566","https://github.com/bcgit/bc-csharp/commit/212d06474166d5e85be72c2dd4898313aa5dd5f3","https://github.com/bcgit/bc-csharp/commit/99afef612458f70f28e7824a09719bfc3a169bda"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-63566","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-63566","identifiers":["CVE-2026-63566"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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Not a global EPSS backfill.","generation":"2026-11-11T19:58:45.4661486+00:00","complete":true,"records":1097,"lastAttemptAt":"2026-11-11T19:58:45.4661486+00:00","lastSuccessAt":"2026-11-11T19:58:45.6274866+00:00","error":null,"lastVerifiedAt":"2026-11-11T19:58:45.6274869+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-0feae4fee9a0467f9dde710515b6c624","complete":false,"records":13753,"lastAttemptAt":"2026-11-11T19:59:11.1509472+00:00","lastSuccessAt":"2026-11-11T19:59:11.147+00:00","error":"100 identifier lookups failed; latest failures include request timeout. 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