#VU49022 Information disclosure in Mozilla Firefox and Firefox ESR - CVE-2020-35111

Vulnerability identifier: #VU49022

Vulnerability risk: Medium

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

CVE-ID: CVE-2020-35111

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

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

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the proxy.onRequest API does not use proxy when viewing source code of the web application. A remote attacker, who controls the web server can obtain user's real IP address, if the user decides to view the web application source code while behind a proxy server.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 83.0

Firefox ESR: 60.0 - 60.9.0, 68.0 - 68.12.0, 78.0 - 78.5.0

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2020-54/
https://www.mozilla.org/en-US/security/advisories/mfsa2020-55/

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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.