Vulnerability identifier: #VU55684

Vulnerability risk: High

CVSSv3.1: 7.9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2021-29985

CWE-ID: CWE-416

Exploitation vector: Network

Exploit availability: Yes

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 code on the target system.

The vulnerability exists due to a use-after-free error in media channels within the MediaCacheStream::NotifyDataReceived method. A remote attacker can trick the victim to open a specially crafted web page, trigger a use-after-free error and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 60.0 - 90.0.2

Firefox ESR: 78.0 - 78.12.0, 68.0 - 68.12.0, 60.0 - 60.9.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2021-33/
http://www.mozilla.org/en-US/security/advisories/mfsa2021-34/

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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. However, proof of concept for this vulnerability is available.