// For flags

CVE-2021-40528

libgcrypt: ElGamal implementation allows plaintext recovery

Severity Score

5.9
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

1
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

-
*SSVC
Descriptions

The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

Una implementación de ElGamal en Libgcrypt versiones anteriores a 1.9.4, permite una recuperación de texto plano porque, durante la interacción entre dos bibliotecas criptográficas, una determinada combinación peligrosa del primo definido por la clave pública del receptor, el generador definido por la clave pública del receptor y los exponentes efímeros del emisor puede conllevar a un ataque de configuración cruzada contra OpenPGP.

A flaw was found in libgcrypt's ElGamal implementation, where it allows plain text recovery. During the interaction between two cryptographic libraries, a certain combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP. The highest threat from this vulnerability is to confidentiality.

*Credits: N/A
CVSS Scores
Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
Attack Vector
Network
Attack Complexity
High
Authentication
None
Confidentiality
Partial
Integrity
None
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:-
Exploitation
-
Automatable
-
Tech. Impact
-
* Organization's Worst-case Scenario
Timeline
  • 2021-09-06 CVE Reserved
  • 2021-09-06 CVE Published
  • 2024-05-22 EPSS Updated
  • 2024-08-04 CVE Updated
  • 2024-08-04 First Exploit
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
CWE
  • CWE-327: Use of a Broken or Risky Cryptographic Algorithm
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Gnupg
Search vendor "Gnupg"
Libgcrypt
Search vendor "Gnupg" for product "Libgcrypt"
< 1.9.4
Search vendor "Gnupg" for product "Libgcrypt" and version " < 1.9.4"
-
Affected