Zero-day vulnerability in Mozilla Firefox

Use-after-free
CVE-2020-6820

Vulnerability details

Advisory: SB2020040320 - Remote code execution in Mozilla Firefox and Firefox ESR

Vulnerable component: Mozilla Firefox

CVE-ID: CVE-2020-6820

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-416 - Use After Free

Description:

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error caused by a race condition handling ReadableStream. A remote attacker can create a specially crafted website, trick the victim into visiting it, trigger a use-after-free error and execute arbitrary code on the system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Note, this vulnerability is being actively exploited in the wild in targeted attacks.

External links:

https://www.mozilla.org/en-US/security/advisories/mfsa2020-11/


About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.