Ubuntu 20.04 LTS / 22.04 LTS / 23.10 : NSS vulnerabilities (USN-6727-1)

medium Nessus Plugin ID 193171


The remote Ubuntu host is missing one or more security updates.


The remote Ubuntu 20.04 LTS / 22.04 LTS / 23.10 host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-6727-1 advisory.

- 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. (CVE-2023-4421)

- NSS was susceptible to a timing side-channel attack when performing RSA decryption. This attack could potentially allow an attacker to recover the private data. This vulnerability affects Firefox < 124, Firefox ESR < 115.9, and Thunderbird < 115.9. (CVE-2023-5388)

- Multiple NSS NIST curves were susceptible to a side-channel attack known as Minerva. This attack could potentially allow an attacker to recover the private key. This vulnerability affects Firefox < 121.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.


Update the affected libnss3, libnss3-dev and / or libnss3-tools packages.

See Also


Plugin Details

Severity: Medium

ID: 193171

File Name: ubuntu_USN-6727-1.nasl

Version: 1.0

Type: local

Agent: unix

Published: 4/10/2024

Updated: 4/10/2024

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus

Risk Information


Risk Factor: Medium

Score: 4.4


Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:N/AC:L/Au:S/C:C/I:N/A:N

CVSS Score Source: CVE-2023-4421


Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:20.04:-:lts, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, cpe:/o:canonical:ubuntu_linux:23.10, p-cpe:/a:canonical:ubuntu_linux:libnss3, p-cpe:/a:canonical:ubuntu_linux:libnss3-dev, p-cpe:/a:canonical:ubuntu_linux:libnss3-tools

Required KB Items: Host/cpu, Host/Debian/dpkg-l, Host/Ubuntu, Host/Ubuntu/release

Exploit Ease: No known exploits are available

Patch Publication Date: 4/10/2024

Vulnerability Publication Date: 10/12/2023

Reference Information

CVE: CVE-2023-4421, CVE-2023-5388, CVE-2023-6135

USN: 6727-1