Remote code execution via post-storage extension validation
Published Aug 25, 2021 · Updated Aug 4, 2024
File upload flaws in Umbraco Forms 4.0.0 through 8.7.5 allow remote attackers to execute code or delete arbitrary server files. The upload handler writes a user-supplied file under App_Data before checking its extension, allowing a crafted web.config to override directory restrictions; a separate unvalidated hidden path controls cleanup deletion. A publicly reachable form containing an upload field is required, and successful code execution runs commands with the web server process's privileges.
Summary
What happened
File upload flaws in Umbraco Forms 4.0.0 through 8.7.5 allow remote attackers to execute code or delete arbitrary server files. The upload handler writes a user-supplied file under App_Data before checking its extension, allowing a crafted web.config to override directory restrictions; a separate unvalidated hidden path controls cleanup deletion. A publicly reachable form containing an upload field is required, and successful code execution runs commands with the web server process's privileges.
The record
- CVE
- CVE-2021-37334
- Published
- Aug 25, 2021
- Updated
- Aug 4, 2024
- Vendor
- Unknown vendor
- Product
- Unknown product
- Classifications
- T1190, T1505.003
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 25, 2021CVE publishedPublication date reported by the CVE source.
- Aug 4, 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?
What conditions does exploitation require?
What is affected?
Affected products and versions are unavailable in this record.
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.
Public exploit references
- AppCheck Umbraco Forms file-upload exploit demonstrationfunctional · demonstrated
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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