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VulnerabilityPublished

CVE-2026-59646: Legion of the Bouncy Castle BC-JAVA · Excessive Memory Allocation

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 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.85, 2.73.12, 2.1.24 +2
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 bctls to 1.85; BC-LTS-JAVA and bctls-lts8on to 2.73.12; BC-FJA to 2.1.24, 2.0.24 or 1.0.24.

Affected software

ProductAffectedFixed in
Legion of the Bouncy Castle Inc.BC-JAVAAffected
  • <1.85
Fixed in
  • 1.85
Legion of the Bouncy Castle Inc.BC-LTS-JAVAAffected
  • >=2.73.0 <2.73.12
Fixed in
  • 2.73.12
Legion of the Bouncy Castle Inc.BC-FJAAffected
  • >=2.1.0 <2.1.24
Fixed in
  • 2.1.24
Legion of the Bouncy Castle Inc.BC-FJAAffected
  • >=2.0.0 <2.0.24
Fixed in
  • 2.0.24
Legion of the Bouncy Castle Inc.BC-FJAAffected
  • >=1.0.0 <1.0.24
Fixed in
  • 1.0.24
GitHubbctlspkg:github/bctlsOther threatsAffected
  • <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.

AI-suggested

If you cannot patch yet, consider mitigating exposure by restricting access to affected services or applying any recommended temporary mitigations from the vendor.

Description

A high-severity vulnerability (CVE-2026-59646) exists in Bouncy Castle for Java (BC-JAVA) where the DTLS handshake reassembler allocates a buffer based on an unchecked 24-bit length value. This affects versions before 1.85 and versions from 2.73.0 up to but not including 2.73.12, including certain FIPS series releases. The unchecked allocation can lead to excessive memory allocation, classified under CWE-789.

References

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