FTP file modification via CRLF command injection
Published Nov 14, 2023 · Updated Oct 9, 2025
Command injection in System.Net.Requests in affected .NET products allows remote authenticated users to write or delete FTP files. FormatFtpCommand concatenates URI-derived FTP parameters without rejecting embedded CRLF delimiters, allowing extra commands. Reachability requires an application to pass an untrusted FTP URI to System.Net.WebRequest.Create and backend FTP access; commands use that FTP session's permissions.
Summary
What happened
Command injection in System.Net.Requests in affected .NET products allows remote authenticated users to write or delete FTP files. FormatFtpCommand concatenates URI-derived FTP parameters without rejecting embedded CRLF delimiters, allowing extra commands. Reachability requires an application to pass an untrusted FTP URI to System.Net.WebRequest.Create and backend FTP access; commands use that FTP session's permissions.
The record
- CVE
- CVE-2023-36049
- Published
- Nov 14, 2023
- Updated
- Oct 9, 2025
- Vendor
- Microsoft
- Product
- Microsoft .NET Framework 3.5 and 4.8.1
- Classifications
- CWE-20, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Nov 14, 2023CVE publishedPublication date reported by the CVE source.
- Oct 9, 2025Record 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=4.8.1 <4.8.9206.0
What conditions does exploitation require?
What is affected?
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.
Public exploit references
- ZDI CRLF injection demonstrationproof of concept · 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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