#VU47195 Improper Certificate Validation in Mozilla NSS - CVE-2019-11727

Vulnerability identifier: #VU47195

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-11727

CWE-ID: CWE-295

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla NSS
Universal components / Libraries / Libraries used by multiple products

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to perform MitM attack.

The vulnerability exists doe to an error within the Mozilla NSS library, when working with TLS certificates. A remote attacker can force Network Security Services (NSS) to sign CertificateVerify with PKCS#1 v1.5 signatures when those are the only ones advertised by server in CertificateRequest in TLS 1.3. A remote attacker can perform a Man-in-the-Middle attack and gain access to sensitive information.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla NSS: 3.40 - 3.44.1

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External links
https://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html
https://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html
https://lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html
https://lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html
https://lists.opensuse.org/opensuse-security-announce/2020-01/msg00006.html
https://access.redhat.com/errata/RHSA-2019:1951
https://bugzilla.mozilla.org/show_bug.cgi?id=1552208
https://security.gentoo.org/glsa/201908-12
https://www.mozilla.org/security/advisories/mfsa2019-21/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.