DTLS handshake reassembler allocates buffer from unchecked 24-bit length
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.
CVE-2026-63566
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-63566
bc-csharp
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://github.com/bcgit/bc-csharp",
"vendor": "Legion of the Bouncy Castle Inc.",
"product": "bc-csharp",
"versions": [
{
"status": "affected",
"version": "0",
"lessThan": "2.7.0",
"versionType": "semver"
}
],
"packageName": "BouncyCastle.Cryptography",
"programFiles": [
"crypto/src/tls/DtlsReliableHandshake.cs",
"crypto/src/tls/DtlsReassembler.cs"
],
"collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
"defaultStatus": "unaffected"
}
]- Related CVEs
- CVE-2026-63566
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #8107 · Revision 1
- Added to Heist Feed
- Publisher date