CVE-2023-4421

Name	CVE-2023-4421
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.
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DLA-3634-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
nss (PTS)	buster	2:3.42.1-1+deb10u5	vulnerable
	buster (security)	2:3.42.1-1+deb10u8	fixed
	bullseye (security), bullseye	2:3.61-1+deb11u3	fixed
	bookworm	2:3.87.1-1	fixed
	sid, trixie	2:3.99-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
nss	source	buster	2:3.42.1-1+deb10u7		DLA-3634-1
nss	source	(unstable)	2:3.61-1

Notes

https://bugzilla.mozilla.org/show_bug.cgi?id=1651411
https://bugzilla.redhat.com/show_bug.cgi?id=2238677
https://hg.mozilla.org/projects/nss/rev/fc05574c739947d615ab0b2b2b564f01c922eccd