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Mozilla Firefox CVE-2026-16365

| EUVDEUVD-2026-46196 HIGH
Improper Privilege Management (CWE-269)
2026-07-21 mozilla GHSA-534q-w7ff-7vh6
Privilege Escalation Mozilla
8.8
CVSS 3.1 · Vendor: mozilla
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Severity by source

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

Remote web content over the network (AV:N), but a browser-rendering/Workers flaw realistically requires the victim to load attacker content, so UI:R; high CIA impact retained for a privilege-escalation/sandbox-boundary compromise.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/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 HIGH
qualitative

Primary rating from Vendor (mozilla).

CVSS VectorVendor: mozilla

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

Lifecycle Timeline

7
Re-analysis Queued
Jul 24, 2026 - 21:22 vuln.today
cvss_changed
Severity Changed
Jul 24, 2026 - 21:22 NVD
CRITICAL HIGH
CVSS changed
Jul 24, 2026 - 21:22 NVD
9.8 (CRITICAL) 8.8 (HIGH)
Analysis Generated
Jul 22, 2026 - 17:10 vuln.today
CVSS changed
Jul 22, 2026 - 16:22 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

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153.

AnalysisAI

Privilege escalation in Mozilla Firefox's DOM: Workers component lets remote attackers gain elevated privileges within the browser through web-facing content, potentially enabling sandbox/privilege boundary compromise. The flaw was resolved in Firefox 153 and is described in Mozilla advisory MFSA2026-68. There is no public exploit identified at time of analysis, and the EPSS score is low (0.14%, 4th percentile), indicating no evidence of active or imminent widespread exploitation.

Technical ContextAI

The vulnerability resides in Firefox's DOM Web Workers implementation - the browser subsystem that runs JavaScript on background threads separated from the main page thread, communicating via structured message passing. CWE-269 (Improper Privilege Management) is the root-cause class, meaning the Workers code assigns or fails to correctly enforce a privilege boundary, allowing script or a compromised context to operate with more privilege than intended (a common route to content-process privilege escalation or sandbox escape in modern multi-process browsers). The CPE cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:* identifies the affected product as Firefox with an unbounded version range up to the fix, and Mozilla is the reporting/originating source (self-reported via Bugzilla bug 2049149).

RemediationAI

Vendor-released patch: Firefox 153 - upgrade all Firefox installations to 153 or later, which is the definitive fix per MFSA2026-68 (https://www.mozilla.org/security/advisories/mfsa2026-68/). Because Firefox auto-updates by default, ensure automatic updates are enabled and force a restart to apply the update fleet-wide; for managed/enterprise (ESR or policy-locked) deployments, push the patched build through your update management channel and confirm the running version. No documented pre-patch workaround exists for this specific Workers flaw; if immediate patching is impossible, compensating controls include restricting browsing to trusted sites via web-content filtering/proxy policy and disabling untrusted JavaScript with a content-security extension - noting the trade-off that broad JavaScript restriction breaks most modern web applications and is disruptive to users.

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Same weakness CWE-269 – Improper Privilege Management

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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Module for Desktop Applications 15 SP7 Affected
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected

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CVE-2026-16365 vulnerability details – vuln.today
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