Authenticated code execution via unchecked f_dir copy
Published Mar 16, 2026 · Updated Mar 16, 2026
Stack-based buffer overflow in D-Link NAS and NVR firmware 20260205 and earlier allows remote authenticated users to execute code or crash devices. The UPnP_AV_Server_Path_Setting handler in /cgi-bin/app_mgr.cgi copies the attacker-controlled f_dir parameter into a fixed-size stack buffer without length validation, overwriting the return address. The demonstrated request carries an administrative session cookie; the proof of concept reliably crashes the appliance, while return-address control supports arbitrary-code execution.
Summary
What happened
Stack-based buffer overflow in D-Link NAS and NVR firmware 20260205 and earlier allows remote authenticated users to execute code or crash devices. The UPnP_AV_Server_Path_Setting handler in /cgi-bin/app_mgr.cgi copies the attacker-controlled f_dir parameter into a fixed-size stack buffer without length validation, overwriting the return address. The demonstrated request carries an administrative session cookie; the proof of concept reliably crashes the appliance, while return-address control supports arbitrary-code execution.
The record
- CVE
- CVE-2026-4214
- Published
- Mar 16, 2026
- Updated
- Mar 16, 2026
- Vendor
- D-Link
- Product
- DNR-322L
- Classifications
- CWE-119, CWE-121, CWE-787, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 16, 2026CVE publishedPublication date reported by the CVE source.
- Mar 16, 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=20260205
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
- D-Link app_mgr.cgi f_dir overflow proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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