CVE-2021-23974 Cross-site scripting in Firefox

What is CVE-2021-23974?

CVE-2021-23974 is a medium-severity cross-site scripting vulnerability in Mozilla Firefox, published on 26 Feb 2021. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

The DOMParser API did not properly process '<noscript>' elements for escaping. This could be used as an mXSS vector to bypass an HTML Sanitizer. This vulnerability affects Firefox < 86.

Which versions are affected by CVE-2021-23974?

It affects 1 product.

Products include Mozilla Firefox.

How do I fix CVE-2021-23974?

Upgrade to a fixed version.

Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.

Is CVE-2021-23974 being exploited?

There is no known exploitation of CVE-2021-23974 in the wild and no public exploit code.

Other vulnerabilities in Mozilla Firefox

• CVE-2019-11708 Mozilla Firefox and Thunderbird Sandbox Escape Exploited Critical 10.0
• CVE-2010-3765 Mozilla Multiple Products Remote Code Execution Exploited Critical 9.8
• CVE-2022-26486 Mozilla Firefox Use-After-Free Exploited Critical 9.6
• CVE-2022-26485 Mozilla Firefox Use-After-Free Exploited High 8.8
• CVE-2019-11707 Mozilla Firefox and Thunderbird Type Confusion Exploited High 8.8

All Mozilla Firefox vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-xgvx-m8xh-737m, UBUNTU-CVE-2021-23974.