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Mozilla Firefox CVE-2026-16369

| EUVDEUVD-2026-46202 CRITICAL
Integer Overflow or Wraparound (CWE-190)
2026-07-21 mozilla GHSA-54w4-5mrc-hfp8
Buffer Overflow Integer Overflow Red Hat Mozilla
Critical
Disputed · 9.8 Vendor: mozilla
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Severity by source

Sources disagree (Medium–Critical)
Vendor (mozilla) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.5 HIGH

Client-side browser bug needs the victim to visit malicious content (UI:R) and integer-overflow-to-RCE typically requires heap grooming (AC:H); full C/I/A impact assumed for content-process code execution.

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
CRITICAL
qualitative
Red Hat
7.5 MEDIUM
qualitative

vuln.today treats the vendor’s rating as authoritative. A higher third-party CVSS (e.g. CISA-ADP) is shown for transparency but does not drive the headline severity.

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

4
Analysis Generated
Jul 22, 2026 - 19:36 vuln.today
CVSS changed
Jul 22, 2026 - 18:22 NVD
9.8 (CRITICAL)
CVE Published
Jul 21, 2026 - 12:37 cve.org
UNKNOWN (no severity yet)
CVE Published
Jul 21, 2026 - 12:37 cve.org
CRITICAL 9.8

DescriptionCVE.org

Integer overflow in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 153 and Firefox ESR 140.13.

AnalysisAI

Memory corruption in Mozilla Firefox's JavaScript WebAssembly engine, stemming from an integer overflow (CWE-190), can be triggered by attacker-controlled web content and was patched in Firefox 153 and Firefox ESR 140.13. Reported by Mozilla and tracked as EUVD-2026-46202/MFSA2026-68 & MFSA2026-70, the flaw carries a 9.8 CVSS rating implying potential remote code execution, though no public exploit identified at time of analysis and EPSS exploitation probability is low at 0.15% (5th percentile).

Technical ContextAI

The defect lives in Firefox's WebAssembly (Wasm) implementation within the SpiderMonkey JavaScript engine. WebAssembly is a low-level bytecode format executed in-browser at near-native speed, and its runtime performs extensive size/offset arithmetic when allocating linear memory, decoding modules, and bounds-checking accesses. An integer overflow (CWE-190) in this arithmetic means a computed length or offset wraps past its maximum value, producing an undersized allocation or a bypassed bounds check that leads to out-of-bounds read/write. The affected component is identified by CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* - i.e., the Firefox browser (all versions prior to the fixed builds), with the parallel ESR train patched in 140.13. Because Wasm can be delivered and instantiated by any web page, the attack surface is reachable purely through rendered content.

RemediationAI

Vendor-released patch: upgrade to Firefox 153 or Firefox ESR 140.13, which contain the fix; update immediately via automatic updates or managed enterprise deployment (MSI/GPO, ESR channel for regulated fleets). Refer to Mozilla advisories MFSA2026-68 (https://www.mozilla.org/security/advisories/mfsa2026-68/) and MFSA2026-70 (https://www.mozilla.org/security/advisories/mfsa2026-70/) for release confirmation. If patching must be delayed, a targeted compensating control is to disable WebAssembly by setting javascript.wasm to false in about:config (via policy for fleets), which removes the vulnerable code path at the cost of breaking Wasm-dependent sites (some web apps, games, and PDF/media tooling); a broader but heavier option is enforcing strict script controls or an isolation/remote-browsing layer for untrusted browsing. Avoid rendering untrusted web content on unpatched builds in the interim.

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Same weakness CWE-190 – Integer Overflow or Wraparound

View all
CVE-2013-2729 CRITICAL POC
9.8
CVE-2015-8651 HIGH
8.8
CVE-2012-5054 HIGH POC
8.8
CVE-2014-0569 CRITICAL POC
9.3
CVE-2023-21716 CRITICAL POC
9.8
CVE-2017-3599 HIGH POC
7.5
CVE-2017-7529 HIGH
7.5
CVE-2016-1010 HIGH
8.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Affected
SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected

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CVE-2026-16369 vulnerability details – vuln.today
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