Medium severity · published Dec 12, 2023
CVE-2023-4421
The NSS code used for checking PKCS#1 v1.5 was leaking information useful in mounting Bleichenbacher-like attacks
6.5
CVSS
0.8%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 55% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
NS
Nss · Mozilla
before 3.6.1 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-4421
CVE.org
https://www.cve.org/CVERecord?id=CVE-2023-4421
Issue Tracking
https://bugzilla.mozilla.org/show_bug.cgi?id=1651411
Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2023-53/
lists.debian.org
https://lists.debian.org/debian-lts-announce/2023/10/msg00039.html
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