Security restrictions bypass in Mozilla Firefox - CVE-2021-23986
Published: March 23, 2021
Vulnerability identifier: #VU51666
CSH Severity: Low
CVSS v4: 2.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2021-23986
CWE-ID: CWE-264
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to application does not properly impose security restrictions. A malicious extension with the 'search' permission could have installed a new search engine whose favicon referenced a cross-origin URL. The response to this cross-origin request could have been read by the extension, allowing a same-origin policy bypass by the extension, which should not have cross-origin permissions. This cross-origin request was made without cookies, so the sensitive information disclosed by the violation was limited to local-network resources or resources that perform IP-based authentication.
Affected software
Mozilla Firefox
Gentoo Linux
Ubuntu
firefox (Ubuntu package)
Gentoo Linux
Ubuntu
firefox (Ubuntu package)
How to mitigate CVE-2021-23986
Install updates from vendor's website.
Mozilla Firefox - update to 87.0
firefox (Ubuntu package) - addressed in versions 87.0+build3-0ubuntu0.16.04.2, 87.0+build3-0ubuntu0.18.04.2, 87.0+build3-0ubuntu0.20.04.2, 87.0+build3-0ubuntu0.20.10.1
firefox (Ubuntu package) - addressed in versions 87.0+build3-0ubuntu0.16.04.2, 87.0+build3-0ubuntu0.18.04.2, 87.0+build3-0ubuntu0.20.04.2, 87.0+build3-0ubuntu0.20.10.1