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Mozilla Firefox CVE-2026-12308

| EUVDEUVD-2026-37099 MEDIUM
Buffer Overflow (CWE-119)
2026-06-16 mozilla GHSA-q9cv-r3xr-8wvv
Buffer Overflow Mozilla
Medium
Disputed · 5.3 Vendor: mozilla
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Severity by source

Sources disagree (Medium–Critical)
Vendor (mozilla) PRIMARY
5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
vuln.today AI
4.3 MEDIUM

Browser memory safety flaws require user to navigate to attacker-controlled content (UI:R); no integrity or availability impact applies per description.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
SUSE
CRITICAL
qualitative
Red Hat
6.1 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
Low
Integrity
None
Availability
None

Lifecycle Timeline

3
Analysis Generated
Jul 23, 2026 - 16:43 vuln.today
CVE Published
Jun 16, 2026 - 11:52 cve.org
MEDIUM 5.3
CVE Published
Jun 16, 2026 - 11:52 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152 and Firefox ESR 140.12.

AnalysisAI

Memory safety vulnerability (CWE-119) in Mozilla Firefox prior to version 152 and Firefox ESR prior to 140.12 allows remote unauthenticated attackers to achieve partial information disclosure via a crafted web interaction that triggers an out-of-bounds memory operation. The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) reflects network reachability without credentials, though impact is confined to limited confidentiality loss with no integrity or availability consequences. No public exploit code has been identified, EPSS stands at 0.28% (19th percentile), and CISA has not listed this in the Known Exploited Vulnerabilities catalog - signals that consistently point to low near-term exploitation risk.

Technical ContextAI

CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) encompasses buffer overflows, over-reads, and related memory corruption classes. In a browser engine like Firefox, this class of flaw typically manifests in content parsing subsystems - JavaScript engine internals, media codec handling, DOM layout, or network protocol processing - where attacker-controlled data can influence buffer boundary calculations. The CPE string cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* confirms all Firefox versions up to (but not including) 152 are within scope, with Firefox ESR covered separately up to 140.12. The presence of Red Hat and SUSE tags indicates these distributions ship Firefox packages and were tracking downstream backport requirements. The Bugzilla reference (bug 2038302) points to the upstream fix commit, though the exact code-level subsystem is not disclosed in the available data.

RemediationAI

Upgrade Mozilla Firefox to version 152 or later, or upgrade Firefox ESR to version 140.12 or later. These are the vendor-confirmed fix versions per Mozilla Security Advisories MFSA2026-57 (https://www.mozilla.org/security/advisories/mfsa2026-57/), MFSA2026-58 (https://www.mozilla.org/security/advisories/mfsa2026-58/), MFSA2026-60 (https://www.mozilla.org/security/advisories/mfsa2026-60/), and MFSA2026-61 (https://www.mozilla.org/security/advisories/mfsa2026-61/). Red Hat and SUSE users should apply distribution-channel Firefox security updates rather than upstream tarballs to maintain package signing and support. If immediate patching is operationally blocked, deploying browser isolation (e.g., virtual desktop infrastructure or containerized browsing) reduces exposure at the cost of infrastructure overhead. No specific feature-level disable workaround is documented for this class of memory safety flaw; feature disablement is not a viable substitute for patching.

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Same weakness CWE-119 – Buffer Overflow

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CVE-2023-4966 HIGH POC
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Same technique Buffer Overflow

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CVE-2017-7269 CRITICAL POC
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9.8
CVE-2015-3113 CRITICAL POC
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CVE-2020-0796 CRITICAL POC
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CVE-2019-11043 CRITICAL POC
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CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Critical
Product Status
openSUSE Tumbleweed Fixed
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

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CVE-2026-12308 vulnerability details – vuln.today
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