Quick answers
- Is CVE-2026-63571 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-63571 being exploited in the wild.
- How severe is CVE-2026-63571?
- Informational severity, published 2 October 2026.
- Which products and versions are affected?
- Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography before 2.7.0.
- Is there a fix for CVE-2026-63571?
- Yes: fixed in BouncyCastle.Cryptography 2.7.0. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-63571 attacked?
- It is attacked over the network, in a software library.
- Am I affected by CVE-2026-63571?
- Check whether you run Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography 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.
How to fix
- Fixed in: BouncyCastle.Cryptography 2.7.0
Technical details
The PkixAttrCertPathValidator and PkixAttrCertPathBuilder classes in bc-csharp fail to verify the cryptographic signature of the attribute certificate against the issuer's public key, despite checking other aspects like holder/issuer paths, validity periods, extensions, and revocation status per RFC 3281. An attacker can submit a forged attribute certificate where the issuer field names a trusted authority but the signature is invalid or absent. Only applications explicitly using these classes to validate attribute certificates are affected.
Affected products
- Legion of the Bouncy Castle Inc. BouncyCastle.Cryptography before 2.7.0
Timeline
- 2026-10-02: disclosed