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.
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Affected Vendors & Products
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History
Tue, 27 Oct 2026 16:45:00 +0000
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| First Time appeared |
Bouncycastle
Bouncycastle bc-csharp |
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| CPEs | cpe:2.3:a:bouncycastle:bc-csharp:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Bouncycastle
Bouncycastle bc-csharp |
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cvssV3_1
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Sun, 04 Oct 2026 22:15:00 +0000
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Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-csharp |
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| Vendors & Products |
Legion Of The Bouncy Castle Inc.
Legion Of The Bouncy Castle Inc. bc-csharp |
Sat, 03 Oct 2026 06:30:00 +0000
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ssvc
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Fri, 02 Oct 2026 07:15:00 +0000
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| 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. | |
| Title | DTLS handshake reassembler allocates buffer from unchecked 24-bit length | |
| Weaknesses | CWE-789 | |
| References |
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| Metrics |
cvssV4_0
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Status: PUBLISHED
Assigner: bcorg
Published: 2026-10-02T06:57:21.718Z
Updated: 2026-10-02T18:08:57.485Z
Reserved: 2026-07-16T23:48:46.075Z
Link: CVE-2026-63566
Updated: 2026-10-02T18:08:43.262Z
Status : Analyzed
Published: 2026-10-02T07:16:36.973
Modified: 2026-10-27T16:25:06.960
Link: CVE-2026-63566
No data.