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.
Published 2023-12-12 17:15:08
Updated 2023-12-20 18:40:25
View at NVD,   CVE.org

Products affected by CVE-2023-4421

Exploit prediction scoring system (EPSS) score for CVE-2023-4421

0.06%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 30 %
Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2023-4421

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
6.5
MEDIUM CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
2.8
3.6
NIST

CWE ids for CVE-2023-4421

  • The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor, which exposes security-relevant information about the state of the product, such as whether a particular operation was successful or not.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2023-4421

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