Skip to main content

Mozilla Firefox CVE-2026-12315

| EUVDEUVD-2026-37106 CRITICAL
Protection Mechanism Failure (CWE-693)
2026-06-16 mozilla GHSA-9j9w-q224-vc26
Authentication Bypass Mozilla Red Hat Suse
Critical
Disputed · 9.1 Vendor: mozilla
Share

Severity by source

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

Browser bug triggered by loading attacker content (UI:R), bypassing same-origin protections (S:C) to read and tamper with other origins' data (C:H/I:H); no availability impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

Lifecycle Timeline

3
Analysis Generated
Jun 16, 2026 - 20:22 vuln.today
CVSS changed
Jun 16, 2026 - 20:22 NVD
9.1 (CRITICAL)
CVE Published
Jun 16, 2026 - 11:52 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Mitigation bypass in the DOM: Security component. This vulnerability was fixed in Firefox 152 and Firefox ESR 140.12.

Articles & Coverage 1

News Critical Security Mitigation Bypass in Mozilla Firefox - CVE-2026-12315 Jun 16, 2026

AnalysisAI

Security mitigation bypass in the DOM: Security component of Mozilla Firefox allows remote attackers to circumvent browser security controls, with high impact to confidentiality and integrity. The flaw affects Firefox versions prior to 152 and Firefox ESR prior to 140.12, with no public exploit identified at time of analysis. Given the CVSS 9.1 rating and network-reachable attack vector, any user browsing a malicious page is potentially exposed.

Technical ContextAI

The vulnerability resides in the DOM: Security component of Gecko, the browser engine underlying Firefox (cpe:2.3:a:mozilla:firefox). This subsystem implements security primitives such as the same-origin policy, Content Security Policy enforcement, and other DOM-level isolation mechanisms that prevent untrusted web content from acting outside its sandboxed origin. CWE-693 (Protection Mechanism Failure) indicates that one of these defensive controls can be bypassed entirely rather than overflowed or corrupted, meaning an attacker reaches a state the security model was designed to forbid. Because Firefox ESR 140.12 is also patched, the regression appears to extend back into the long-term-support branch used by enterprise and Tor Browser downstreams.

RemediationAI

Vendor-released patch: upgrade to Firefox 152 or Firefox ESR 140.12, both of which contain the fix per the Mozilla Foundation Security Advisories at https://www.mozilla.org/security/advisories/mfsa2026-57/ and mfsa2026-58/ (with related details at mfsa2026-60/ and mfsa2026-61/). Enterprises pinned to ESR should validate 140.12 in staging because the bypass touches DOM security and any add-ons or enterprise policies that rely on legacy origin behavior may need re-testing. Until patching is complete, compensating controls include enforcing strict Content Security Policy headers on internally hosted apps, restricting outbound browsing to vetted destinations via web proxy categorization, and disabling auto-loading of remote subresources where feasible - noting that these measures protect only internal properties and do not prevent users from visiting attacker-controlled sites on the open web. Downstream consumers of ESR (notably Tor Browser and some Linux distribution packages) should track their respective vendor rebuilds rather than installing upstream Firefox directly.

More in Mozilla

View all
CVE-2015-4495 HIGH POC
8.8 Aug 08

The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote
CVE-2013-1690 HIGH POC
8.8 Jun 26

Mozilla Firefox before 22.0, Firefox ESR 17.x before 17.0.7, Thunderbird before 17.0.7, and Thunderbird ESR 17.x before

CVE-2013-0758 CRITICAL POC
9.3 Jan 13

Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderb
CVE-2013-0753 CRITICAL POC
9.3 Jan 13

Use-after-free vulnerability in the serializeToStream implementation in the XMLSerializer component in Mozilla Firefox b
CVE-2012-3993 CRITICAL POC
9.3 Oct 10

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 16.0, Firefox ESR 10.x before 10.0.8, Thunderbi
CVE-2013-1710 CRITICAL POC
10.0 Aug 07

The crypto.generateCRMFRequest function in Mozilla Firefox before 23.0, Firefox ESR 17.x before 17.0.8, Thunderbird befo
CVE-2017-3823 HIGH POC
8.8 Feb 01

An issue was discovered in the Cisco WebEx Extension before 1.0.7 on Google Chrome, the ActiveTouch General Plugin Conta
CVE-2014-8636 HIGH POC
7.5 Jan 14

The XrayWrapper implementation in Mozilla Firefox before 35.0 and SeaMonkey before 2.32 does not properly interact with

CVE-2013-0757 CRITICAL POC
9.3 Jan 13

The Chrome Object Wrapper (COW) implementation in Mozilla Firefox before 18.0, Firefox ESR 17.x before 17.0.2, Thunderbi
CVE-2014-1510 CRITICAL POC
9.8 Mar 19

The Web IDL implementation in Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and Se
CVE-2014-1511 CRITICAL POC
9.8 Mar 19

Mozilla Firefox before 28.0, Firefox ESR 24.x before 24.4, Thunderbird before 24.4, and SeaMonkey before 2.25 allow remo
CVE-2013-0643 HIGH
8.8 Feb 27

The Firefox sandbox in Adobe Flash Player before 10.3.183.67 and 11.x before 11.6.602.171 on Windows and Mac OS X, and b

Same weakness CWE-693 – Protection Mechanism Failure

View all
CVE-2013-2465 CRITICAL POC
9.8
CVE-2013-0431 MEDIUM POC
5.3
CVE-2025-40536 HIGH POC
8.1
CVE-2026-21513 HIGH
8.8
CVE-2026-21510 HIGH POC
8.8
CVE-2026-32202 MEDIUM POC
4.3
CVE-2017-10952 HIGH POC
8.8
CVE-2022-32845 CRITICAL POC
10.0

Same technique Authentication Bypass

View all
CVE-2023-22515 CRITICAL POC
9.8
CVE-2012-4681 CRITICAL POC
9.8
CVE-2013-2465 CRITICAL POC
9.8
CVE-2011-3544 CRITICAL POC
9.8
CVE-2025-61882 CRITICAL POC
9.8
CVE-2024-0012 CRITICAL POC
9.3
CVE-2023-46805 HIGH POC
8.2
CVE-2012-1723 CRITICAL POC
9.8

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

Share

CVE-2026-12315 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy