Improper Certificate Validation Affecting org.bouncycastle:bcprov-jdk18on package, versions [,1.85)
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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- published4 Aug 2026
- disclosed3 Aug 2026
- creditUnknown
Introduced: 3 Aug 2026
NewCVE-2026-8763 (opens in a new tab)How to fix?
Upgrade org.bouncycastle:bcprov-jdk18on to version 1.85 or higher.
Overview
Affected versions of this package are vulnerable to Improper Certificate Validation in the isEmailConstrained() and isURIConstrained() methods of PKIXNameConstraintValidator, which compare rfc822Name and URI subjectAltName values with a bare equalsIgnoreCase() and do not strip a trailing dot the way the dNSName path does. An attacker who controls a name-constrained intermediate CA can issue certificates for email and URI hosts that an excludedSubtrees constraint was meant to block, for example ceo@bank.com. against an exclusion of bank.com, by appending a trailing dot so the value no longer matches the constraint. This affects only the email and URI constraint paths and not dNSName, and it requires a relying party to validate certificate paths through this validator with name constraints in force.