Vulnerability 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.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Nss | < 3.6.1 |
Related Weaknesses (CWE)
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1651411Issue Tracking
- https://www.mozilla.org/security/advisories/mfsa2023-53/Issue TrackingVendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1651411Issue Tracking
- https://lists.debian.org/debian-lts-announce/2023/10/msg00039.html
- https://www.mozilla.org/security/advisories/mfsa2023-53/Issue TrackingVendor Advisory
FAQ
What is CVE-2023-4421?
CVE-2023-4421 is a vulnerability with a CVSS score of 6.5 (MEDIUM). 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 me...
How severe is CVE-2023-4421?
CVE-2023-4421 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2023-4421?
Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Nss.