Privilege escalation through undisclosed Netmonitor flaw
Published Mar 24, 2026 · Updated Mar 24, 2026
Netmonitor privilege escalation in Firefox before 149 and Thunderbird before 149 allows remote attackers to gain elevated application privileges. Firefox ESR before 140.9 and Thunderbird before 140.9 are also affected, but Mozilla has not published the flawed Netmonitor operation or the input that triggers it. The published unauthenticated network assessment requires no user interaction, while Mozilla rates the issue moderate and does not define the resulting privilege boundary.
Summary
What happened
Netmonitor privilege escalation in Firefox before 149 and Thunderbird before 149 allows remote attackers to gain elevated application privileges. Firefox ESR before 140.9 and Thunderbird before 140.9 are also affected, but Mozilla has not published the flawed Netmonitor operation or the input that triggers it. The published unauthenticated network assessment requires no user interaction, while Mozilla rates the issue moderate and does not define the resulting privilege boundary.
The record
- CVE
- CVE-2026-4717
- Published
- Mar 24, 2026
- Updated
- Mar 24, 2026
- Vendor
- Mozilla
- Product
- Firefox
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 24, 2026CVE publishedPublication date reported by the CVE source.
- Mar 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <149
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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