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CVE-2026-4687

HIGH CVSS 3.1: 8.6 EPSS 0.02%
Updated Mar 25, 2026
Mozilla
Parameter Value
CVSS 8.6 (HIGH)
Affected Versions 128.0 — 149.0
Fixed In 115.34.0
Type CWE-754, CWE-120 (Buffer Copy without Checking Size)
Vendor Mozilla
Public PoC No

Sandbox escape due to incorrect boundary conditions in the Telemetry component. This vulnerability affects Firefox < 149, Firefox ESR < 115.34, Firefox ESR < 140.9, Thunderbird < 149, and Thunderbird < 140.9.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
None
No data leak
Integrity
None
No data modification
Availability
High
Complete denial of service

CVSS Vector v3.1

Vulnerable Products 3

Configuration From (including) Up to (excluding)
Mozilla Firefox
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
115.34.0
Mozilla Firefox
cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
149.0
Mozilla Firefox
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
128.0 140.9.0