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Mozilla Firefox CVE-2026-7321

| EUVDEUVD-2026-26058 CRITICAL
Classic Buffer Overflow (CWE-120)
2026-04-28 mozilla
Buffer Overflow Mozilla Suse Red Hat
Critical
Disputed · 9.6 NVD
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Severity by source

Sources disagree (Medium–Critical)
NVD PRIMARY
9.6 CRITICAL
AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
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 VectorNVD

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

Lifecycle Timeline

6
Re-analysis Queued
Apr 28, 2026 - 20:23 vuln.today
cvss_changed
Analysis Generated
Apr 28, 2026 - 17:00 vuln.today
CVSS changed
Apr 28, 2026 - 15:22 NVD
9.6 (CRITICAL)
EUVD ID Assigned
Apr 28, 2026 - 14:30 euvd
EUVD-2026-26058
Analysis Generated
Apr 28, 2026 - 14:30 vuln.today
CVE Published
Apr 28, 2026 - 13:49 nvd
CRITICAL 9.6

DescriptionCVE.org

Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox ESR 140.10.1.

AnalysisAI

Sandbox escape in Mozilla Firefox's WebRTC networking component allows remote attackers to break out of browser process isolation and execute code outside the sandbox with high integrity and confidentiality impact. Firefox ESR 140.10.1 fixes this critical boundary condition flaw (CWE-120). User interaction is required (visiting a malicious site), but no authentication is needed. EPSS data not provided. Not listed in CISA KEV at time of analysis, indicating no confirmed widespread active exploitation.

Technical ContextAI

WebRTC (Web Real-Time Communication) implements peer-to-peer audio, video, and data channels directly in browsers without plugins. The networking component handles ICE candidate gathering, STUN/TURN protocols, and UDP/TCP connectivity establishment. This vulnerability stems from a boundary condition error (CWE-120), a class of bugs where code fails to properly validate input size or index bounds before buffer operations. In WebRTC networking code, such flaws often occur in packet parsing, codec handling, or DTLS handshake processing. The CPE string (cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*) indicates Mozilla Firefox as the affected product, with version boundaries defined by the fix in ESR 140.10.1. The changed scope (S:C) in the CVSS vector confirms this is a sandbox escape - the vulnerability impacts resources beyond the original security context, breaking Firefox's multi-process architecture (Fission/e10s) that isolates web content from the parent process.

RemediationAI

Upgrade to Firefox ESR 140.10.1 or later immediately, as confirmed by Mozilla Security Advisory MFSA2026-36 at https://www.mozilla.org/security/advisories/mfsa2026-36/. For rapid-release channel users, update to the corresponding patched mainline Firefox version (check mozilla.org for version mapping). Organizations using managed deployments should prioritize this update due to sandbox escape impact. If immediate patching is not possible, implement compensating controls: disable WebRTC entirely via about:config by setting media.peerconnection.enabled to false (trade-off: breaks video conferencing, WebRTC applications like Google Meet, Zoom web client, and real-time communication features), restrict browser usage to trusted sites only via allowlist policies, or deploy network-layer WebRTC blocking by filtering UDP ports 3478, 5349, and port ranges 49152-65535 used for STUN/TURN and RTP (trade-off: same functionality loss, may impact legitimate business applications). These mitigations should be temporary only as they severely limit browser functionality.

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Same weakness CWE-120 – Classic Buffer Overflow

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Same technique Buffer Overflow

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CVE-2012-1889 HIGH POC
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Vendor StatusVendor

SUSE

Severity: Critical
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Module for Package Hub 15 SP7 Affected
SUSE Linux Enterprise Server 16.0 Affected
SUSE Linux Enterprise Workstation Extension 15 SP7 Affected
SUSE Linux Enterprise Server 15 SP7 Affected

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CVE-2026-7321 vulnerability details – vuln.today
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