CVE-2026-6779 — Improper Input Validation in Mozilla Firefox

CWE-20 — Improper Input ValidationCWE-79 — Cross-site ScriptingCWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer8 documents7 sources
Severity
5.3MEDIUMNVD
EPSS
0.1%
top 73.69%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla FirefoxMozilla Thunderbird
Timeline
PublishedApr 21
Latest updateApr 28

Description

Other issue in the JavaScript Engine component. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitability: 3.9 | Impact: 1.4

Affected Packages2 packages

▶Mozillamozilla/firefox< Firefox 150
▶Mozillamozilla/thunderbird< Thunderbird 150

🔴Vulnerability Details

2
VulDB
Mozilla Firefox up to 149 JavaScript Engine Remote Code Execution (Nessus ID 310633)↗2026-04-28
▶
GHSA
GHSA-xp4p-9mc9-5c47: Other issue in the JavaScript Engine component↗2026-04-21
▶

📋Vendor Advisories

3
Red Hat
JavaScript Engine: Firefox: Firefox: Unspecified vulnerability in JavaScript Engine↗2026-04-21
▶
Mozilla
Mozilla Foundation Security Advisory 2026-33: CVE-2026-6779↗
▶
Mozilla
Mozilla Foundation Security Advisory 2026-30: CVE-2026-6779↗
▶

💬Community

1
Bugzilla
CVE-2026-6779 JavaScript Engine: Firefox: Firefox: Unspecified vulnerability in JavaScript Engine↗2026-04-21
▶
CVE-2026-6779 — Improper Input Validation in Mozilla | cvebase