OAuth flow interception via incorrect redirect validation
Published Dec 9, 2025 · Updated Apr 13, 2026
Same-origin policy bypass in affected Firefox and Thunderbird releases allows remote attackers to intercept WebExtension OAuth flows. The ext-identity.js redirect guard combines browser-element checks with AND, accepting requests from attacker-controlled tabs that fetch a predictable extension redirect URL. Exploitation requires an extension to invoke launchWebAuthFlow and precise timing; a forged OAuth result can bind the extension to an attacker-controlled account and divert synchronized user data.
Summary
What happened
Same-origin policy bypass in affected Firefox and Thunderbird releases allows remote attackers to intercept WebExtension OAuth flows. The ext-identity.js redirect guard combines browser-element checks with AND, accepting requests from attacker-controlled tabs that fetch a predictable extension redirect URL. Exploitation requires an extension to invoke launchWebAuthFlow and precise timing; a forged OAuth result can bind the extension to an attacker-controlled account and divert synchronized user data.
The record
- CVE
- CVE-2025-14331
- Published
- Dec 9, 2025
- Updated
- Apr 13, 2026
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- CWE-346
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 9, 2025CVE publishedPublication date reported by the CVE source.
- 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Mozilla launchWebAuthFlow interception reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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