CVE-2026-4692Public exploitNetwork attack vector

Sandbox escape via unchecked Responsive Design Mode flag

Published Mar 24, 2026 · Updated Mar 24, 2026

Sandbox escape in Mozilla Firefox, Firefox ESR, and Thunderbird allows attackers with a compromised content process to control privileged UI. BrowsingContext lacks a CanSet check for InRDMPane, so a child process can claim Responsive Design Mode and send negative-coordinate touch events outside content. Affected releases are Firefox before 149, Firefox ESR before 115.34 or 140.9, and Thunderbird before 149 or 140.9.

CVSS severity10.0
Critical
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox escape in Mozilla Firefox, Firefox ESR, and Thunderbird allows attackers with a compromised content process to control privileged UI. BrowsingContext lacks a CanSet check for InRDMPane, so a child process can claim Responsive Design Mode and send negative-coordinate touch events outside content. Affected releases are Firefox before 149, Firefox ESR before 115.34 or 140.9, and Thunderbird before 149 or 140.9.

The record

CVE
CVE-2026-4692
Published
Mar 24, 2026
Updated
Mar 24, 2026
Vendor
Mozilla
Product
Firefox
Classifications
CWE-653, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=unspecified <149

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <149
Mozilla · Thunderbirdversion=unspecified <140.9; version=unspecified <149
Mozilla · Firefox ESRversion=unspecified <115.34; version=unspecified <140.9

Published CVSS scores

9.6CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
10.0NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
7.5Red HatCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-653Improper Isolation or Compartmentalization
T1068Exploitation for Privilege Escalation

Public exploit references

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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