#VU61104 Time-of-check Time-of-use (TOCTOU) Race Condition in Mozilla Firefox and Firefox ESR - CVE-2022-26387

Vulnerability identifier: #VU61104

Vulnerability risk: Medium

CVSSv4.0: 2.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-26387

CWE-ID: CWE-367

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 perform spoofing attack.

The vulnerability exists due to a race condition when verifying signatures during Firefox add-on installation. A remote attacker can replace the underlying add-on file while the user was confirming the prompt and install a malicious add-on on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 90.0 - 97.0.2

Firefox ESR: 91.0 - 91.6.1

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External links
https://www.mozilla.org/en-US/security/advisories/mfsa2022-10/
https://www.mozilla.org/en-US/security/advisories/mfsa2022-11/

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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.