Vulnerability · Published Jan 16, 2024 · Assigned by GitHub_M
CVE-2022-31021Unlinkability broken in ursa when verifiers use malicious keys
Low 3.3
In plain English
A low-severity security flaw in ursa from hyperledger. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities).
Official description
Ursa is a cryptographic library for use with blockchains. A weakness in the Hyperledger AnonCreds specification that is not mitigated in the Ursa and AnonCreds implementations is that the Issuer does not publish a key correctness proof demonstrating that a generated private key is sufficient to meet the unlinkability guarantees of AnonCreds. The Ursa and AnonCreds CL-Signatures implementations always generate a sufficient private key. A malicious issuer could in theory create a custom CL Signature implementation (derived from the Ursa or AnonCreds CL-Signatures implementations) that uses weakened private keys such that presentations from holders could be shared by verifiers to the issuer who could determine the holder to which the credential was issued. This vulnerability could impact holders of AnonCreds credentials implemented using the CL-signature scheme in the Ursa and AnonCreds implementations of CL Signatures. The ursa project has has moved to end-of-life status and no fix is expected.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| hyperledger | ursa | <= 0.3.7 |
Weakness: CWE-829 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
References
- https://github.com/hyperledger/ursa/security/advisories/GHSA-2q6j-gqc4-4gw3 x_refsource_CONFIRM
- https://www.brics.dk/RS/98/29/BRICS-RS-98-29.pdf x_refsource_MISC