# CVE-2026-15055: Bouncy Castle PKCS#8 PBES2 unbounded KDF cost vulnerability

Source: https://junglewise.ai/threats/cve-2026-15055-bouncy-castle-pkcs-8-pbes2-unbounded-kdf-cost-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-03. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-15055 · Severity: high · CVSS 8.2 · Published 2026-08-03

Bouncy Castle is a widely-used cryptographic library that handles encrypted key storage. This vulnerability allows an attacker to craft a malicious encrypted private key file that forces the decryption process to consume excessive CPU resources, causing denial of service. Any application using Bouncy Castle to decrypt password-protected keys could hang or crash when processing an attack payload.

Technologies: [Bouncy Castle for Java](https://junglewise.ai/threats/technologies/bouncy-castle-for-java), [Bouncy Castle for Java FIPS](https://junglewise.ai/threats/technologies/bouncy-castle-for-java-fips), [Bouncycastle Bouncy Castle For Java Lts](https://junglewise.ai/threats/technologies/bouncy-castle-for-java-lts). Vendors: [Bouncy Castle](https://junglewise.ai/threats/vendors/bouncy-castle), [Bouncycastle](https://junglewise.ai/threats/vendors/bouncycastle).

## Quick answers

**Is CVE-2026-15055 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-15055 being exploited in the wild.

**How severe is CVE-2026-15055?** High severity, with a CVSS score of 8.2, published 3 August 2026.

**Which products and versions are affected?** Bouncy Castle for Java before 1.85; Bouncy Castle for Java FIPS bcpkix-fips before 1.0.12 (1.0.X series), 2.0.12 (2.0.X series), 2.1.12 (2.1.X series).

**Is there a fix for CVE-2026-15055?** 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.

**How is CVE-2026-15055 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-15055?** Check whether you run Bouncy Castle for Java, Bouncy Castle for Java FIPS or Bouncycastle Bouncy Castle For Java Lts at an affected version. 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.

## Technical details

The vulnerability exists in Bouncy Castle's PKCS#8 PBES2 decryption implementation, which fails to validate or bound the KDF (Key Derivation Function) cost parameter in encrypted input. An attacker can supply a crafted PBES2-encrypted private key with an arbitrarily large iteration count, forcing the library to perform unbounded expensive cryptographic operations. This is a denial-of-service vulnerability accessible to any user who can provide input to the decryption function; no authentication or privilege escalation is possible. The issue affects Bouncy Castle for Java before 1.85, Java LTS before 2.73.12, and FIPS variants in multiple series. Patches are available from the vendor.

## Affected products

- Bouncy Castle Bouncy Castle for Java before 1.85
- Bouncy Castle Bouncy Castle for Java LTS before 2.73.12
- Bouncy Castle Bouncy Castle for Java FIPS bcpkix-fips before 1.0.12 (1.0.X series), 2.0.12 (2.0.X series), 2.1.12 (2.1.X series)

## Timeline

- 2026-08-03: disclosed

## References

- [https://www.bouncycastle.org/download/bouncy-castle-java/](https://www.bouncycastle.org/download/bouncy-castle-java/)
- [https://www.bouncycastle.org/download/bouncy-castle-java-lts/](https://www.bouncycastle.org/download/bouncy-castle-java-lts/)

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