CVE-2023-4421
The NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks.
Does this matter?
Lower severity and a low EPSS score (0.63%). Track it; it rarely justifies an emergency change on its own.
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 3.1
- 6.5 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
- EPSS
- 0.63% probability · 48th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-203
- Affected
- mozilla/nss
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1651411Issue Tracking
- https://www.mozilla.org/security/advisories/mfsa2023-53/Issue Tracking, Vendor 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 Tracking, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.