CVE-2024-1563Public exploitNetwork attack vector

Cross-origin script execution via custom-scheme race

Published Feb 22, 2024 · Updated Mar 27, 2025

Universal cross-site scripting in Mozilla Firefox Focus for iOS before 122 allows remote attackers to execute scripts in a top-origin page. The external open-url handler accepts a javascript URI through the firefox-focus scheme while a background navigation timeout changes the active origin. Exploitation requires opening the crafted custom-scheme link from another app after Focus begins a timed background navigation, enabling attacker script to read or alter content under the resulting top origin.

CVSS severity8.1
High
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Universal cross-site scripting in Mozilla Firefox Focus for iOS before 122 allows remote attackers to execute scripts in a top-origin page. The external open-url handler accepts a javascript URI through the firefox-focus scheme while a background navigation timeout changes the active origin. Exploitation requires opening the crafted custom-scheme link from another app after Focus begins a timed background navigation, enabling attacker script to read or alter content under the resulting top origin.

The record

CVE
CVE-2024-1563
Published
Feb 22, 2024
Updated
Mar 27, 2025
Vendor
Mozilla
Product
Firefox Focus
Classifications
CWE-367, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 22, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 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 <122

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefox Focusversion=unspecified <122

Published CVSS scores

8.1CISA-ADPCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/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 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-367Time-of-check Time-of-use (TOCTOU) Race Condition
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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