XSS via dynamic redirect URI validation bypass
Published Sep 8, 2026 · Updated Sep 10, 2026
Cross-site scripting in XenForo before 2.3.13 allows remote attackers to execute JavaScript in the board origin via a crafted redirect URI. The dynamic redirect handler accepts a javascript URI whose authority embeds the board hostname and whose percent-encoded newlines evade host and scheme filtering. Execution occurs when an authenticated user performs a Follow action, limiting the consequence to attacker-supplied script running in that user's board-origin browser context.
Summary
What happened
Cross-site scripting in XenForo before 2.3.13 allows remote attackers to execute JavaScript in the board origin via a crafted redirect URI. The dynamic redirect handler accepts a javascript URI whose authority embeds the board hostname and whose percent-encoded newlines evade host and scheme filtering. Execution occurs when an authenticated user performs a Follow action, limiting the consequence to attacker-supplied script running in that user's board-origin browser context.
The record
- CVE
- CVE-2026-73319
- Published
- Sep 8, 2026
- Updated
- Sep 10, 2026
- Vendor
- XenForo Ltd.
- Product
- XenForo
- Classifications
- T1189
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 8, 2026CVE publishedPublication date reported by the CVE source.
- Sep 10, 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?
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- Affected versionversion=0 <2.3.13
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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