Vulnerability CVE-2021-33560


Published: 2021-06-08

Description:
Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. (There is also an interoperability problem because the selection of the k integer value does not properly consider the differences between basic ElGamal encryption and generalized ElGamal encryption.) This, for example, affects use of ElGamal in OpenPGP.

Type:

CWE-203

(Information Exposure Through Discrepancy)

CVSS2 => (AV:N/AC:L/Au:N/C:P/I:N/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5/10
2.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
None
None
Affected software
Gnupg -> Libgcrypt 

 References:
https://dev.gnupg.org/T5466
https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61
https://dev.gnupg.org/T5305
https://dev.gnupg.org/T5328

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