CVE-2023-4421

6.5 MEDIUM
Published: December 12, 2023 Modified: November 04, 2025

Description

The NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks. Both the overall correctness of the padding as well as the length of the encrypted message was leaking through timing side-channel. By sending large number of attacker-selected ciphertexts, the attacker would be able to decrypt a previously intercepted PKCS#1 v1.5 ciphertext (for example, to decrypt a TLS session that used RSA key exchange), or forge a signature using the victim's key. The issue was fixed by implementing the implicit rejection algorithm, in which the NSS returns a deterministic random message in case invalid padding is detected, as proposed in the Marvin Attack paper. This vulnerability affects NSS < 3.61.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1651411
Source: security@mozilla.org
Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2023-53/
Source: security@mozilla.org
Issue Tracking Vendor Advisory
https://bugzilla.mozilla.org/show_bug.cgi?id=1651411
Source: af854a3a-2127-422b-91ae-364da2661108
Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2023-53/
Source: af854a3a-2127-422b-91ae-364da2661108
Issue Tracking Vendor Advisory

5 reference(s) from NVD

Quick Stats

CVSS v3 Score
6.5 / 10.0
EPSS (Exploit Probability)
0.2%
48th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

mozilla