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Advisory details: gitlab / maven/org.bouncycastle/bctls-jdk15to18/CVE-2026-59646
Advisory ID gitlab/maven/org.bouncycastle/bctls-jdk15to18/CVE-2026-59646
Aliases CVE-2026-59646
Summary DTLS handshake reassembler allocates buffer from unchecked 24-bit length Affects Bouncy Castle for Java before 1.85. DTLSReliableHandshake.processRecord() allocates a reassembly buffer sized from the 24-bit handshake length field of an incoming record, without the maximum-message-size check the stream-TLS path applies. Up to sixteen message sequences may be buffered per connection, so a single record of about 205 bytes carrying sixteen fragment headers with a maximal length forces roughly 256 MiB of allocation before any authentication. A few small UDP datagrams can drive the JVM to OutOfMemoryError.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (3)
CWE-789 Memory Allocation with Excessive Size Value
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3.1 https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.bouncycastle/bctls-jdk15to18/CVE-2026-59646.yml
Reference id Reference type URL
https://github.com/bcgit/bc-java/commit/2d98721e71bbd822ffa0f84e088eea645cf679fa
https://github.com/bcgit/bc-java/commit/2ea38942c7917f6d7ab4de93d8a5336d021df0d9
CVE-2026-59646 https://github.com/bcgit/bc-java/wiki/CVE-2026-59646
CVE-2026-59646 https://nvd.nist.gov/vuln/detail/CVE-2026-59646
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.bouncycastle/bctls-jdk15to18/CVE-2026-59646.yml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

There are no SSVC decisions available.