What’s Vulnerable › Vulnerabilities

CVE-2026-59644: MLS hash-ratchet honours arbitrary 32-bit generation counter from sender

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-03 · updated 2026-10-23
• Weakness: CWE-834

Description

In Bouncy Castle for Java before 1.85, MLS hash-ratchet honours arbitrary 32-bit generation counter from sender.

Affected products

• Legion of the Bouncy Castle Inc. BC-JAVA: before 1.85 — fixed in 1.85

How to fix

Upgrade to a fixed version: Legion of the Bouncy Castle Inc. BC-JAVA 1.85. Check the vendor advisory for mitigations.

References

• https://github.com/bcgit/bc-java/commit/610d8757d855afe197df0de6d831cb75c81e3b9f
• https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2%80%9059644

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