CVE-2026-59644
Received Received - Intake

Bouncy Castle Java MLS Hash-Ratchet Generation Counter Validation Bypass

Publication date: 2026-08-03

Last updated on: 2026-08-03

Assigner: bcorg

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

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Meta Information

Published
2026-08-03
Last Modified
2026-08-03
Generated
2026-08-03
AI Q&A
2026-08-03
EPSS Evaluated
N/A
NVD
CVE-2026-59644
EUVD
EUVD-2026-52030

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
bouncy_castle bcprov_jdk15on to 1.85 (exc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-834 The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.

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Executive Summary

In Bouncy Castle for Java before version 1.85, there is a vulnerability in the MLS hash-ratchet mechanism where it incorrectly accepts an arbitrary 32-bit generation counter provided by the sender. This could allow an attacker to manipulate the hash-ratchet process by sending a counter value of their choice.

Detection Guidance

Detection requires checking the Bouncy Castle library version in use. Commands like 'mvn dependency:tree' for Maven projects or inspecting the JAR manifest can verify if the version is below 1.85. No specific network detection commands are provided.

Impact Analysis

This vulnerability could allow an attacker to disrupt secure communication channels by manipulating the hash-ratchet mechanism. If exploited, it might lead to unauthorized access, data tampering, or loss of confidentiality in encrypted communications.

Compliance Impact

This vulnerability could impact compliance with GDPR and HIPAA by compromising the integrity and confidentiality of sensitive data. If exploited, it may lead to unauthorized access to personal or health information, resulting in potential legal and regulatory penalties.

Mitigation Strategies

Upgrade Bouncy Castle to version 1.85 or later immediately. Remove or replace any affected versions in your dependencies or runtime environment to prevent exploitation.

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