Phishing via inline HTML attachment serving
Published Nov 13, 2021 · Updated Aug 3, 2024
Dangerous file upload in BookStack before 21.10.3 allows remote authenticated users to serve attacker-controlled HTML attachments inline. The inlineDownloadResponse path trusts finfo's detected MIME type and returns uploaded HTML with an inline disposition instead of restricting it to a web-safe type. Exploitation requires attachment-upload permission and a victim who opens the attachment, enabling phishing content to display from the trusted BookStack origin.
Summary
What happened
Dangerous file upload in BookStack before 21.10.3 allows remote authenticated users to serve attacker-controlled HTML attachments inline. The inlineDownloadResponse path trusts finfo's detected MIME type and returns uploaded HTML with an inline disposition instead of restricting it to a web-safe type. Exploitation requires attachment-upload permission and a victim who opens the attachment, enabling phishing content to display from the trusted BookStack origin.
The record
- CVE
- CVE-2021-3915
- Published
- Nov 13, 2021
- Updated
- Aug 3, 2024
- Vendor
- BookStack
- Product
- BookStack
- Classifications
- CWE-434
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 13, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record 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=unspecified <21.10.3
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
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Technologies
Your stack
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Your stack
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