#VU24061 Algorithm Downgrade in Mozilla Firefox - CVE-2019-17023

Vulnerability identifier: #VU24061

Vulnerability risk: Low

CVSSv4.0: 1.7 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2019-17023

CWE-ID: CWE-757

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to bypass certain security restrictions.

The vulnerability exists due to insecure negotiation After a HelloRetryRequest in Mozilla NSS that can lead to selection of a less secure protocol (e.g. TLS 1.2 or below) after the HelloRetryRequest TLS 1.3 is sent.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 65.0 - 71.0

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2020-01/

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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.