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Information Exposure Affecting nss-softokn package, versions <0:3.53.1-6.48.amzn1

0.0
medium

Snyk CVSS

    Attack Complexity Low
    Confidentiality High

    Threat Intelligence

    EPSS 0.05% (17th percentile)
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NVD
6.5 medium
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Red Hat
6.5 medium

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  • Snyk ID SNYK-AMZN201803-NSSSOFTOKN-6033791
  • published 25 Oct 2023
  • disclosed 12 Dec 2023
Report a new vulnerability Found a mistake?

Introduced: 25 Oct 2023

CVE-2023-4421 Open this link in a new tab
CWE-208 Open this link in a new tab

How to fix?

Upgrade Amazon-Linux:2018.03 nss-softokn to version 0:3.53.1-6.48.amzn1 or higher.
This issue was patched in ALAS-2023-1858.

NVD Description

Note: Versions mentioned in the description apply only to the upstream nss-softokn package and not the nss-softokn package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2018.03 relevant fixed versions and status.

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.