CVE-2025-5020Public exploitNetwork attack vector

Address spoofing via unrestricted widget deep links

Published May 21, 2025 · Updated Apr 13, 2026

URL scheme authorization flaws in Firefox for iOS before 139 allow remote attackers to spoof website addresses through malicious links. The widgetMediumQuickLinkOpenUrl and widgetSmallQuickLinkOpenUrl deep-link handlers accept non-HTTP schemes without restricting their URL arguments to HTTP or HTTPS. Exploitation requires a user to open a crafted link from another app and then activate browser state, after which attacker-controlled content can appear under a spoofed address.

CVSS severity4.3
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

URL scheme authorization flaws in Firefox for iOS before 139 allow remote attackers to spoof website addresses through malicious links. The widgetMediumQuickLinkOpenUrl and widgetSmallQuickLinkOpenUrl deep-link handlers accept non-HTTP schemes without restricting their URL arguments to HTTP or HTTPS. Exploitation requires a user to open a crafted link from another app and then activate browser state, after which attacker-controlled content can appear under a spoofed address.

The record

CVE
CVE-2025-5020
Published
May 21, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-939, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

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.

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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-939Improper Authorization in Handler for Custom URL Scheme
T1204.001Malicious Link

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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