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VulnerabilityPublished

CVE-2026-59644: Legion of the Bouncy Castle BC-JAVA · Excessive Iteration

Affects Legion of the Bouncy Castle BC-JAVASource CVE Database V5

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Not known to be exploited · CVSS 8.7 High : upgrade to 1.85 soon.

Data as of 31 Oct 2026, 08:20 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.85
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Amber

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 3 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade BC-JAVA and bcmls to 1.85.

Affected software

ProductAffectedFixed in
Legion of the Bouncy Castle Inc.BC-JAVAAffected
  • >=1.73 <1.85
Fixed in
  • 1.85
GitHubbcmlspkg:github/bcmlsOther threatsAffected
  • >=1.73 <1.85
Fixed in
  • 1.85

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

CVE-2026-59644 is a high-severity vulnerability in Bouncy Castle for Java (BC-JAVA) versions before 1.85. It involves the MLS hash-ratchet honoring an arbitrary 32-bit generation counter from the sender, leading to excessive iteration. This flaw is categorized under CWE-834 (Excessive Iteration).

References

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