Ursa is a cryptographic library for use with blockchains. The revocation schema that is part of the Ursa CL-Signatures implementations has a flaw that could impact the privacy guarantees defined by the AnonCreds verifiable credential model, allowing a malicious holder of a revoked credential to generate a valid Non-Revocation Proof for that credential as part of an AnonCreds presentation. A verifier may verify a credential from a holder as being "not revoked" when in fact, the holder's credential has been revoked. Ursa has moved to end-of-life status and no fix is expected.

GitHub, Inc. AV:P/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N

GitHub, Inc. CWE-327

GitHub, Inc. https://github.com/hyperledger-archives/ursa/security/advisories/GHSA-r78f-4q2q-hvv4 [No types assigned]