#VU25123 OS Command Injection in Mozilla Firefox and Firefox ESR - CVE-2020-6799

Vulnerability identifier: #VU25123

Vulnerability risk: Medium

CVSSv4.0: 4.8 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-6799

CWE-ID: CWE-78

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 execute arbitrary shell commands on the target system.

The vulnerability exists due to improper input validation when opening PDF links from other applications and Firefox is configured as a default PDF reader. A remote unauthenticated attacker can trick the victim into clicking on a specially crafted link and execute arbitrary OS commands on the system.

Note: This issue only affects Windows operating systems and when Firefox is configured as the default handler for non-default filetypes. Other operating systems are unaffected.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 61.0 - 72.0.2

Firefox ESR: 60.0 - 60.9.0, 68.0 - 68.4.2

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2020-05/
https://www.mozilla.org/en-US/security/advisories/mfsa2020-06/

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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.