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CVE-2023-0361

Published: 15 February 2023

A timing side-channel in the handling of RSA ClientKeyExchange messages was discovered in GnuTLS. This side-channel can be sufficient to recover the key encrypted in the RSA ciphertext across a network in a Bleichenbacher style attack. To achieve a successful decryption the attacker would need to send a large amount of specially crafted messages to the vulnerable server. By recovering the secret from the ClientKeyExchange message, the attacker would be able to decrypt the application data exchanged over that connection.

Notes

AuthorNote
mdeslaur
bionic already contains a sidechannel in RSA decryption because
CVE-2018-16868 is not fixed due to it being too intrusive. We
will ignore this CVE for bionic and earlier also.

Priority

Medium

Cvss 3 Severity Score

7.4

Score breakdown

Status

Package Release Status
gnutls28
Launchpad, Ubuntu, Debian
bionic Ignored
(change too intrusive)
lunar
Released (3.7.8-5ubuntu1)
trusty Ignored
(end of standard support)
focal
Released (3.6.13-2ubuntu1.8)
xenial Ignored
(change too intrusive)
upstream
Released (3.7.8-5,3.8.0)
jammy
Released (3.7.3-4ubuntu1.2)
kinetic
Released (3.7.7-2ubuntu2.1)
Patches:
upstream: https://gitlab.com/gnutls/gnutls/-/commit/80a6ce8ddb02477cd724cd5b2944791aaddb702a
upstream: https://gitlab.com/gnutls/gnutls/-/commit/4b7ff428291c7ed77c6d2635577c83a43bbae558

Severity score breakdown

Parameter Value
Base score 7.4
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact None
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N