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Mozilla Firefox CVE-2026-74961

| EUVDEUVD-2026-60685 CRITICAL
Observable Discrepancy (CWE-203)
2026-08-18 mozilla GHSA-x77f-p4x9-f73c
Information Disclosure Mozilla Red Hat Suse
Critical
Disputed · 9.1 Vendor: mozilla
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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
5.3 MEDIUM

Remote web content (AV:N) but noisy side-channel extraction (AC:H) needing the victim to load a malicious page (UI:R); pure info leak so C:H, I:N, A:N.

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

4
Analysis Generated
Aug 20, 2026 - 18:28 vuln.today
CVSS changed
Aug 20, 2026 - 18:22 NVD
9.1 (CRITICAL)
CVE Published
Aug 18, 2026 - 12:23 cve.org
CRITICAL 9.1
CVE Published
Aug 18, 2026 - 12:23 cve.org
UNKNOWN (no severity yet)

DescriptionCVE.org

Side-channel in the Web Audio component. This vulnerability was fixed in Firefox 154 and Firefox ESR 153.1.

AnalysisAI

Information disclosure via a side-channel in Mozilla Firefox's Web Audio component allows remote, unauthenticated attackers to infer sensitive data that should be isolated between origins by measuring observable timing or behavioral discrepancies. The flaw affects Firefox before 154 and Firefox ESR before 153.1 and is fixed in those releases; no public exploit has been identified and EPSS is low (0.14%, 4th percentile), indicating no evidence of active exploitation.

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Lure victim to malicious page
Delivery
Load Web Audio side-channel script
Exploit
Measure timing/state discrepancies
Execution
Infer isolated confidential data
Impact
Exfiltrate leaked information
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Vulnerability AssessmentAI

Exploitation Exploitation requires the victim to load attacker-controlled web content in a vulnerable Firefox build (before 154, or ESR before 153.1) with the Web Audio API available, which is the default state. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The input CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N, score 9.1) rates this Critical, but the signals conflict and warrant scrutiny: the description and CWE-203 describe a pure side-channel information-disclosure issue, which is inconsistent with the I:H (high integrity impact) in the supplied vector - a side channel leaks data, it does not modify it, so I:H appears overstated and should be verified with the vendor. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker lures a victim to a malicious or compromised web page whose JavaScript uses the Web Audio API to perform precise measurements of audio-processing timing or state. By observing these discrepancies, the script infers data that should be isolated (for example cross-origin or otherwise confidential information), without any authentication or elevated privileges. …
Remediation Vendor-released patch: upgrade to Firefox 154 or, for the extended-support channel, Firefox ESR 153.1, which contain the fix. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: audit Firefox deployment across your organization and identify all systems running Firefox before version 154 or Firefox ESR before version 153.1; prioritize endpoints processing sensitive information. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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Same weakness CWE-203 – Observable Discrepancy

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Same technique Information Disclosure

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CVE-2025-24813 CRITICAL POC
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CVE-2015-1701 HIGH POC
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CVE-2017-0147 HIGH POC
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CVE-2014-6324 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Important
Product Status
Container suse/kiosk/firefox-esr:140.14-75.12 Affected
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Desktop Applications 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed

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CVE-2026-74961 vulnerability details – vuln.today
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