Memory safety bugs fixed in Firefox 150 and Thunderbird 150

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Summary

CVECVE-2026-6784
StatePUBLISHED
Assignermozilla
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-21 13:16:24 UTC
Updated2026-07-15 01:16:55 UTC
DescriptionMemory 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.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

EPSS: 0.003020000 probability, percentile 0.220720000 (date 2026-07-16)

Problem Types: CWE-125 | CWE-416 | CWE-787 | CWE-125 CWE-125 Out-of-bounds Read | CWE-787 CWE-787 Out-of-bounds Write | CWE-416 CWE-416 Use After Free | CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1ADPDECLARED7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1ADPCVSS7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
3.1134c704f-9b21-4f2e-91b3-4a467353bcc0Secondary7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mozilla Firefox All All All All
Application Mozilla Thunderbird All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mozilla Firefox unaffected 150 * rpm Not specified
CNA Mozilla Thunderbird unaffected 150 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 9 Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-6784.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
access.redhat.com/security/cve/CVE-2026-6784 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
www.mozilla.org/security/advisories/mfsa2026-30 [email protected] www.mozilla.org Vendor Advisory
bugzilla.mozilla.org/buglist.cgi [email protected] bugzilla.mozilla.org
www.mozilla.org/security/advisories/mfsa2026-33 [email protected] www.mozilla.org Vendor Advisory
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1536243%2C1745382%2C1851073%2C1893400%2C1963301%2C2001319%2C2002899%2C2012436%2C2014435%2C2016901%2C2019916%2C2020486%2C2020612%2C2020817%2C2021788%2C2022051%2C2022367%2C2022431%2C2023302%2C2023670%2C2024225%2C2024238%2C2024240%2C2024265%2C2024367%2C2024369%2C2024424%2C2024760%2C2025281%2C2025361%2C2025387%2C2025466%2C2025954%2C2025958%2C2026278%2C2026292%2C2026297%2C2026378%2C2027148%2C2027287%2C2027341%2C2027384%2C2027427%2C2027694%2C2027993%2C2028009%2C2028270%2C2028416%2C2028524%2C2029295%2C2029699%2C2029800%2C2029801 MITRE bugzilla.mozilla.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Ben Visness, Brian Grinstead, Christian Holler, Dimi Lee, Jens Stutte, Jim Mathies, John Schanck, Jon Coppeard, Karl Tomlinson, Maurice Dauer, Nika Layzell, Randell Jesup, Tom Schuster and the Mozilla Fuzzing Team (en)

Additional Advisory Data

SourceTimeEvent
ADP2026-04-21T14:01:34.505ZReported to Red Hat.
ADP2026-04-21T12:41:13.111ZMade public.

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