CVE-2026-6784 — Out-of-bounds Read in Mozilla Firefox

CWE-125 — Out-of-bounds ReadCWE-416 — Use After FreeCWE-787 — Out-of-bounds Write6 documents5 sources
Severity
7.5HIGHNVD
EPSS
0.0%
top 87.27%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Mozilla FirefoxMozilla Thunderbird
Timeline
PublishedApr 21

Description

Memory safety bugs present in Firefox 149 and Thunderbird 149. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 150 and Thunderbird 150.

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HExploitability: 1.6 | Impact: 5.9

Affected Packages2 packages

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

🔴Vulnerability Details

1
GHSA
GHSA-fcrv-8vh3-4pg3: Memory safety bugs present in Firefox 149 and Thunderbird 149↗2026-04-21
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📋Vendor Advisories

3
Red Hat
Firefox: Thunderbird: Firefox and Thunderbird: Arbitrary code execution via memory safety bugs↗2026-04-21
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Mozilla
Mozilla Foundation Security Advisory 2026-30: CVE-2026-6784↗
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Mozilla
Mozilla Foundation Security Advisory 2026-33: CVE-2026-6784↗
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💬Community

1
Bugzilla
CVE-2026-6784 Firefox: Thunderbird: Firefox and Thunderbird: Arbitrary code execution via memory safety bugs↗2026-04-21
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CVE-2026-6784 — Out-of-bounds Read in Mozilla Firefox | cvebase