Vulnerability Details : CVE-2023-4421
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.
Products affected by CVE-2023-4421
- cpe:2.3:a:mozilla:nss:*:*:*:*:*:*:*:*
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
-
https://bugzilla.mozilla.org/show_bug.cgi?id=1651411
1651411 - (CVE-2023-4421) New tlsfuzzer code can still detect timing issues in RSA operations.Issue Tracking
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https://www.mozilla.org/security/advisories/mfsa2023-53/
Timing side-channel in PKCS#1 v1.5 decryption depadding code — MozillaIssue Tracking;Vendor Advisory
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