Vulnerability 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.
Related Weaknesses (CWE)
References
- https://github.com/bcgit/bc-csharp/commit/212d06474166d5e85be72c2dd4898313aa5dd5
- https://github.com/bcgit/bc-csharp/commit/99afef612458f70f28e7824a09719bfc3a169b
- https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63566
FAQ
What is CVE-2026-63566?
CVE-2026-63566 is a documented vulnerability. 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 unauthe...
How severe is CVE-2026-63566?
CVSS scoring is not yet available for CVE-2026-63566. Check NVD for updates.
Is there a patch for CVE-2026-63566?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.