CVE-2024-21670

CL-Signatures Revocation Scheme in Ursa has flaws that allow a holder to demonstrate non-revocation of a revoked credential

HIGH
8.1
CVSS Score
Published: January 16, 2024 at 09:44 PM UTC
Updated: June 17, 2026 at 07:09 AM UTC
2 products affected across 2 vendorsUrsaUrsa

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Severity
HIGH8.1
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

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 A verifier may verify a credential from a holder as being "not revoked" when in fact, the holder's credential has been revoked.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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-327

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