CVE-2022-26384Public exploitNetwork attack vector

Sandbox escape via unpropagated browsing-context flags

Published Dec 22, 2022 · Updated Apr 16, 2025

Sandbox bypass in Mozilla Firefox before 98, Firefox ESR before 91.7, and Thunderbird before 91.7 allows remote attackers to execute JavaScript. New top-level browsing contexts failed to inherit the originating context's InitialSandboxFlags, so target=_blank JavaScript links ran without allow-scripts. Exploitation requires control of an allow-popups iframe and a user click; Thunderbird disables scripting while reading email, limiting exposure to browser-like contexts.

CVSS severity9.6
Critical
EPSS probability0.93%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Sandbox bypass in Mozilla Firefox before 98, Firefox ESR before 91.7, and Thunderbird before 91.7 allows remote attackers to execute JavaScript. New top-level browsing contexts failed to inherit the originating context's InitialSandboxFlags, so target=_blank JavaScript links ran without allow-scripts. Exploitation requires control of an allow-popups iframe and a user click; Thunderbird disables scripting while reading email, limiting exposure to browser-like contexts.

The record

CVE
CVE-2022-26384
Published
Dec 22, 2022
Updated
Apr 16, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-693, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record 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 <98

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <98
Mozilla · Thunderbirdversion=unspecified <91.7
Mozilla · Firefox ESRversion=unspecified <91.7

Published CVSS scores

9.6NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
9.6CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-693Protection Mechanism Failure
T1203Exploitation for Client Execution

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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