CVE-2026-63571High· 8.7▾ TwilightImproper verification of cryptographic signature in the attribute certificate path validator (PkixAttrCertPathValidator, also used by PkixAttrCertPathBuilder) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote att…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 47.8 · likelihood 0 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Oct 2.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
0.2%
Improper verification of cryptographic signature in the attribute certificate path validator (PkixAttrCertPathValidator, also used by PkixAttrCertPathBuilder) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to have a forged X.509 attribute certificate accepted as valid, and so obtain whatever roles or privileges an application grants on the strength of its attributes, via an attribute certificate that names a trusted attribute authority as its issuer but was not signed by it, because the RFC 3281 validation steps check the holder and issuer certification paths, validity period, extensions and revocation status but never verify the attribute certificate's signature with the issuer's public key. Only applications that use these classes to validate attribute certificates are affected.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-71891High· 7.1In Bouncy Castle for Java before 1.86, BLS12_381BasicScheme.keyValidate, and so BLSPublicKeyParameters and every BasicScheme, MessageAugmentation and ProofOfPossession verify and aggregateVerify that gate on it, accepted a public key bui…
CVE-2026-71887High· 8.2In Bouncy Castle for Java before 1.86, the high-level OpenPGP API accepted a data signature made by a signing subkey whose Subkey Binding signature carried no embedded Primary Key Binding (cross-certification) signature, in the case wher…
CVE-2026-63570High· 7.1Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in Legion of the Bouncy Castle Inc
CVE-2026-63572High· 7.1Allocation of resources without limits in PKCS#12 keystore loading (Pkcs12Store.Load) in Legion of the Bouncy Castle Inc
CVE-2026-63573High· 8.2Observable discrepancy in the CMS RSA PKCS#1 v1.5 key-transport unwrap (KeyTransRecipientInformation.UnwrapKey) in Legion of the Bouncy Castle Inc
CVE-2026-63574High· 8.7Memory allocation with excessive size value in the OpenPGP signature and user attribute subpacket parsers (SignatureSubpacketsParser.ReadPacket, UserAttributeSubpacketsParser.ReadPacket) in Legion of the Bouncy Castle Inc