CVE-2026-4701 is a critical use-after-free vulnerability found in the JavaScript Engine component, affecting Mozilla Firefox versions prior to 149, Firefox ESR prior to 140.9, and Thunderbird prior to 149 and 140.9. This vulnerability carries a CVSS score of 9.8 Critical, indicating it is network-exploitable with low attack complexity, requiring no user interaction or privileges, and could lead to complete compromise of confidentiality, integrity, and availability. Currently, there is no evidence of active exploitation in the wild (KEV: No) and no public exploit code available on platforms like Metasploit or ExploitDB, though it has received minimal community discussion.
| Vendor | Product | Version(s) | CPE |
|---|---|---|---|
< 140.9.0CPE matchmatch criteria | cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:* | ||
< 149.0CPE matchmatch criteria | cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:* |
CVSS version used by this source: 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.
The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.