# CVE-2026-12852: In Bouncy Castle for Java before 1.85, MLS wire decoder allocates attacker-declared opaque length before bounds check.

Source: https://junglewise.ai/threats/cve-2026-12852-in-bouncy-castle-for-java-before-1-85-mls-wire-decoder-allocates  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-03  
License: CC BY 4.0 with a link back

CVE-2026-12852 · Severity: high · CVSS 7.5 · Published 2026-08-03

In Bouncy Castle for Java before 1.85, MLS wire decoder allocates attacker-declared opaque length before bounds check.

Vendors: [Bouncycastle](https://junglewise.ai/threats/vendors/bouncycastle).

## Quick answers

**Is CVE-2026-12852 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-12852 being exploited in the wild.

**How severe is CVE-2026-12852?** High severity, with a CVSS score of 7.5, published 3 August 2026.

**Which products and versions are affected?** Bouncycastle Bc-Java. The advisory does not name versions.

**Is there a fix for CVE-2026-12852?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-12852?** Check whether you run Bouncycastle Bc-Java. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Bouncycastle Bc-Java