Unauthenticated arbitrary blob creation via missing controller authentication
Published Jul 23, 2026 · Updated Jul 23, 2026
Authentication bypass in Chatwoot before 4.16.0 allows remote attackers to create arbitrary ActiveStorage blobs through direct uploads. The conversation direct uploads controller inherits ActiveStorage::DirectUploadsController without an authentication callback, and its account helper lets unauthenticated requests continue. No account credentials or user interaction are required; a successful request returns a signed PUT URL that writes attacker-chosen bytes to storage and consumes capacity.
Summary
What happened
Authentication bypass in Chatwoot before 4.16.0 allows remote attackers to create arbitrary ActiveStorage blobs through direct uploads. The conversation direct uploads controller inherits ActiveStorage::DirectUploadsController without an authentication callback, and its account helper lets unauthenticated requests continue. No account credentials or user interaction are required; a successful request returns a signed PUT URL that writes attacker-chosen bytes to storage and consumes capacity.
The record
- CVE
- CVE-2026-63765
- Published
- Jul 23, 2026
- Updated
- Jul 23, 2026
- Vendor
- Chatwoot
- Product
- Chatwoot
- Classifications
- CWE-306, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 23, 2026CVE publishedPublication date reported by the CVE source.
- Jul 23, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <4.16.0
What conditions does exploitation require?
What is affected?
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
- Unauthenticated direct-upload HTTP proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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