CVE-2024-21670 | CL-Signatures Revocation Scheme in Ursa has flaws that allow a holder to demonstrate non-revocation of a revoked credential

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 A verifier may verify a credential from a holder as being "not revoked" when in fact, the holder's credential has been revoked.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

Published: 2024-01-16 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2024-21670 is rated Low Risk (35.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.11%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2024-21670

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-03-17 0.17% 0.11% -0.05%
2 2025-01-22 0.09% 0.17% +0.07%
3 2024-01-25 — 0.09% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2024-21670

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:P/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:N Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:H)
They need powerful rights—admin, root, or similar—before this pays off.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 0.2 5.8 [email protected]
8.1 3.1 HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 5.9 [email protected]

Weakness enumeration for CVE-2024-21670

GitHub Security Advisory for CVE-2024-21670

GHSA-r78f-4q2q-hvv4 · Severity: medium · Ecosystem: rust — CL-Signatures Revocation Scheme in Ursa has flaws that allow a holder to demonstrate non-revocation of a revoked credential

Affected software / configurations for CVE-2024-21670

Vendor Product Version Raw CPE
hyperledger ursa 0.1.0 cpe:2.3:a:hyperledger:ursa:0.1.0:*:*:*:*:rust:*:*

References for CVE-2024-21670

cvelogic Threat Intelligence