CVE-2026-4717
Published: 24 March 2026
Description
Privilege escalation in the Netmonitor component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
Mitigating Controls (NIST 800-53 r5)AI
Directly requires timely identification, reporting, and correction of flaws like the privilege escalation vulnerability in Firefox and Thunderbird's Netmonitor component via vendor patches.
Enforces least privilege on processes and components, limiting the scope and impact of privilege escalation even if the Netmonitor vulnerability is exploited.
Provides process isolation to contain privilege escalation attempts within the Netmonitor component, preventing spread to higher-privileged system areas.
Security SummaryAI
CVE-2026-4717 is a privilege escalation vulnerability in the Netmonitor component affecting Mozilla Firefox prior to version 149, Firefox ESR prior to 140.9, Thunderbird prior to 149, and Thunderbird prior to 140.9. The issue has a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating critical severity with network accessibility, low attack complexity, and no requirements for privileges or user interaction.
Remote attackers require no authentication or privileges to exploit this vulnerability over the network. Successful exploitation enables high-impact compromise of confidentiality, integrity, and availability, allowing attackers to escalate privileges within affected applications and potentially gain unauthorized control over the victim's system.
Mozilla security advisories (MFSA 2026-20, 22, 23, and 24) and the associated Bugzilla entry detail the fix applied in the specified versions. Security practitioners should prioritize updating to Firefox 149, Firefox ESR 140.9, Thunderbird 149, or Thunderbird 140.9 to mitigate the vulnerability.
Details
- CWE(s)
Affected Products
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
CVE describes a remote privilege escalation vulnerability with no auth/UI requirements that directly enables T1068 (Exploitation for Privilege Escalation) to gain control within the browser process and host system.