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 A verifier may verify a credential from a holder as being "not revoked" when in fact, the holder\'s credential has been revoked.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.
Metrics
CVSS Version: 3.1 |
Base Score: 6.5 MEDIUM Vector: CVSS:3.1/AV:P/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N
l➤ Exploitability Metrics: Attack Vector (AV)* PHYSICAL Attack Complexity (AC)* HIGH Privileges Required (PR)* HIGH User Interaction (UI)* REQUIRED Scope (S)* CHANGED
l➤ Impact Metrics: Confidentiality Impact (C)* HIGH Integrity Impact (I)* HIGH Availability Impact (A)* NONE
Weakness Enumeration (CWE)
CWE-ID: CWE-327 CWE Name: CWE-327: Use of a Broken or Risky Cryptographic Algorithm Source: hyperledger-archives
Common Attack Pattern Enumeration and Classification (CAPEC)