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Mozilla Firefox CVE-2026-7323

| EUVDEUVD-2026-26060 HIGH
Out-of-bounds Write (CWE-787)
2026-04-28 mozilla
RCE Buffer Overflow Memory Corruption Mozilla
7.3
CVSS 3.1 · Vendor: mozilla
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Severity by source

Vendor (mozilla) PRIMARY
7.3 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
vuln.today AI
7.5 HIGH

Browser memory-corruption needs the victim to load malicious content (UI:R) and reliable exploitation of a fuzzer-found OOB write is non-trivial (AC:H), but successful code execution yields full C/I/A impact.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

4
Analysis Generated
Jul 24, 2026 - 04:24 vuln.today
CVSS changed
Apr 28, 2026 - 19:52 NVD
7.3 (None) 7.3 (HIGH)
EUVD ID Assigned
Apr 28, 2026 - 14:30 euvd
EUVD-2026-26060
CVE Published
Apr 28, 2026 - 13:49 nvd
HIGH 7.3

DescriptionCVE.org

Memory safety bugs present in Firefox ESR 140.10.0, Thunderbird ESR 140.10.0, Firefox 150.0.0 and Thunderbird 150.0.0. 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 150.0.1 and Firefox ESR 140.10.1.

AnalysisAI

Memory corruption in Mozilla Firefox 150.0.0, Firefox ESR 140.10.0, Thunderbird 150.0.0 and Thunderbird ESR 140.10.0 stems from an out-of-bounds write (CWE-787) that Mozilla assessed as potentially exploitable for arbitrary code execution. Mozilla's own engineers discovered the bugs through internal fuzzing/auditing and shipped fixes in Firefox 150.0.1 and Firefox ESR 140.10.1; there is no public exploit identified at time of analysis and EPSS is very low (0.04%). The flaw affects the browser/mail-client rendering engine, so a victim who loads attacker-controlled web content is the realistic trigger despite the raw CVSS vector.

Technical ContextAI

The vulnerability lives in Mozilla's Gecko engine, the shared HTML/CSS/JavaScript rendering and layout core used by both Firefox and Thunderbird (Thunderbird renders message content with the same engine). The tagged root cause is CWE-787 (out-of-bounds write), a memory-safety defect in which the engine writes past the bounds of an allocated buffer - the classic path from a heap/stack overwrite to control-flow hijacking. Mozilla groups several distinct 'memory safety bugs' (Bugzilla 2028537, 2029911, 2031121, 2033602) under this single CVE, a standard practice for defects found via fuzzing where individual exploitability is not proven but memory corruption was observed. The CPE (cpe:2.3:a:mozilla:firefox) confirms the Firefox application as the anchor product, with the corresponding ESR train and Thunderbird sharing the code.

RemediationAI

Vendor-released patch: upgrade to Firefox 150.0.1 or Firefox ESR 140.10.1 (and the corresponding fixed Thunderbird builds) per Mozilla's advisories at https://www.mozilla.org/security/advisories/mfsa2026-35/ and https://www.mozilla.org/security/advisories/mfsa2026-36/; Red Hat and other Linux users should apply the distribution errata (e.g. https://access.redhat.com/errata/RHSA-2026:19153). Because this is a memory-safety fix in the rendering engine there is no clean configuration workaround, but as interim compensating controls you can enforce browser auto-update so clients pull 150.0.1 without user action, and reduce attack surface by disabling JavaScript for untrusted sites or enabling strict/'Safer' content controls (trade-off: many modern sites break) and, for Thunderbird, keeping remote content and HTML message rendering disabled by default (trade-off: degraded message display). These only narrow exposure - patching is the actual remediation.

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Same weakness CWE-787 – Out-of-bounds Write

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CVE-2014-1761 HIGH POC
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CVE-2021-1732 HIGH POC
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CVE-2013-3346 CRITICAL POC
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Same technique RCE

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Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected
SUSE Linux Enterprise Workstation Extension 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected

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CVE-2026-7323 vulnerability details – vuln.today
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