CVE-2025-10530Public exploitNetwork attack vector

WebAuthn prompt spoofing via case-sensitive URI check

Published Sep 16, 2025 · Updated Sep 16, 2025

WebAuthn spoofing in Firefox for Android before 143 allows remote attackers to trigger authentication prompts from crafted links. The Android intent handler compares the blocked fido scheme case-sensitively, so an uppercase FIDO value inside an intent URI bypasses the check and launches the authentication activity. The documented path runs in Firefox for Android; Mozilla also lists Thunderbird before 143 as affected but provides no Thunderbird-specific mechanism.

CVSS severity6.5
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

WebAuthn spoofing in Firefox for Android before 143 allows remote attackers to trigger authentication prompts from crafted links. The Android intent handler compares the blocked fido scheme case-sensitively, so an uppercase FIDO value inside an intent URI bypasses the check and launches the authentication activity. The documented path runs in Firefox for Android; Mozilla also lists Thunderbird before 143 as affected but provides no Thunderbird-specific mechanism.

The record

CVE
CVE-2025-10530
Published
Sep 16, 2025
Updated
Sep 16, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-290, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 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 <143

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <143
Mozilla · Thunderbirdversion=unspecified <143

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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-290Authentication Bypass by Spoofing
T1204.001User Execution: Malicious 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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