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Advisory details: gitlab / maven/org.bouncycastle/bcprov-jdk15to18/CVE-2026-59651
Advisory ID gitlab/maven/org.bouncycastle/bcprov-jdk15to18/CVE-2026-59651
Aliases CVE-2026-59651
Summary BKS keystore accepts legacy version with 16-bit integrity MAC key Affects Bouncy Castle for Java before 1.85. BcKeyStoreSpi.engineLoad() accepts keystore versions 0, 1 and 2, and for versions other than 2 derives MAC parameters from a byte length where a bit length is expected, producing a 16-bit MAC key. The version field comes from the file and the property intended to gate legacy behaviour covered only a separate alias. Anyone able to supply or modify a .bks file can select the weak branch, brute-force the key offline and produce a valid MAC over a modified store, for example injecting a rogue trusted CA.
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-326 Inadequate Encryption Strength
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/bcprov-jdk15to18/CVE-2026-59651.yml
Reference id Reference type URL
CVE-2026-59651 https://github.com/bcgit/bc-java/wiki/CVE-2026-59651
CVE-2026-59651 https://nvd.nist.gov/vuln/detail/CVE-2026-59651
faf5daa6e9b8460f862afc0af1cc0da365f7d4d2 Other https://github.com/bcgit/bc-java/commit/faf5daa6e9b8460f862afc0af1cc0da365f7d4d2
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:H/A:N Found at https://gitlab.com/gitlab-org/advisories-community/-/blob/main/maven/org.bouncycastle/bcprov-jdk15to18/CVE-2026-59651.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.