#VU29452 Input validation error in Mozilla Firefox - CVE-2020-12417

Vulnerability identifier: #VU29452

Vulnerability risk: Medium

CVSSv4.0: 1.2 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-12417

CWE-ID: CWE-20

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 perform cache poisoning attack.

The vulnerability exists due to an error when processing the %2F character in a manifest URL, which results in Firefox's AppCache behavior to become confused and allowe a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 70.0 - 77.0.1

---

External links
https://www.mozilla.org/en-US/security/advisories/mfsa2020-24/

---

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.