// For flags

CVE-2022-31021

Unlinkability broken in ursa when verifiers use malicious keys

Severity Score

5.3
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

1
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

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.

Ursa es una librería criptográfica para usar con blockchains. Una debilidad en la especificación Hyperledger AnonCreds que no se mitiga en las implementaciones Ursa y AnonCreds es que el Emisor no publica una prueba de corrección de clave que demuestre que una clave privada generada es suficiente para cumplir con las garantías de desvinculación de AnonCreds. Las implementaciones Ursa y AnonCreds CL-Signatures siempre generan una clave privada suficiente. En teoría, un emisor malintencionado podría crear una implementación personalizada de CL Signature (derivada de las implementaciones Ursa o AnonCreds CL-Signatures) que utilice claves privadas debilitadas, de modo que los verificadores puedan compartir las presentaciones de los titulares con el emisor, quien podría determinar a qué titular se se emitió la credencial. Esta vulnerabilidad podría afectar a los titulares de credenciales de AnonCreds implementadas utilizando el esquema de firma CL en las implementaciones Ursa y AnonCreds de CL Signatures. El proyecto Ursa ha llegado al estado de fin de vida útil y no se espera ninguna solución.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
Attack Vector
Local
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2022-05-18 CVE Reserved
  • 2024-01-16 CVE Published
  • 2024-01-25 EPSS Updated
  • 2024-08-03 CVE Updated
  • 2024-08-03 First Exploit
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-829: Inclusion of Functionality from Untrusted Control Sphere
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Hyperledger
Search vendor "Hyperledger"
 Ursa
Search vendor "Hyperledger" for product "Ursa"
 < 0.3
Search vendor "Hyperledger" for product "Ursa" and version " < 0.3"
rust
Affected