Improper Certificate Validation Affecting bouncycastle.cryptography package, versions [,2.7.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-DOTNET-BOUNCYCASTLECRYPTOGRAPHY-20537028
- published6 Oct 2026
- disclosed2 Oct 2026
Introduced: 2 Oct 2026
NewCVE-2026-63576 (opens in a new tab)How to fix?
Upgrade BouncyCastle.Cryptography to version 2.7.0 or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation through PkixNameConstraintValidator.ExtractHostFromURL in crypto/src/pkix/PkixNameConstraintValidator.cs. An attacker can bypass URI name constraints during certification path validation by supplying a subjectAltName URI whose path, query, fragment, or userinfo contains characters such as @ or :, causing the extracted host to differ from the URI’s actual host. This lets a name-constrained subordinate CA, or anyone who can obtain certificates from such a CA, issue certificates that evade permitted or excluded uniformResourceIdentifier constraints, undermining the policy checks that rely on those constraints.