CVE-2026-35585
Published: 07 April 2026
Summary
CVE-2026-35585 is a high-severity OS Command Injection (CWE-78) vulnerability in Filebrowser Filebrowser. Its CVSS base score is 7.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 42.5% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 CM-7 (Least Functionality) and SI-10 (Information Input Validation).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Information Input Validation directly mitigates OS command injection by requiring sanitization and validation of filenames containing shell metacharacters before substitution into hook commands.
Least Functionality prohibits or restricts the vulnerable hook system unless essential, aligning with the vendor's mitigation of disabling hooks by default.
Flaw Remediation ensures timely patching to versions (e.g., 2.33.8+) where the hook vulnerability is addressed by default disablement.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
OS command injection in web file manager directly enables RCE via exploitation of public-facing app (T1190) and arbitrary shell command execution (T1059.004).
NVD Description
File Browser is a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. From 2.0.0 through 2.63.1, the hook system in File Browser — which executes administrator-defined shell commands on file events such as…
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upload, rename, and delete — is vulnerable to OS command injection. Variable substitution for values like $FILE and $USERNAME is performed via os.Expand without sanitization. An attacker with file write permission can craft a malicious filename containing shell metacharacters, causing the server to execute arbitrary OS commands when the hook fires. This results in Remote Code Execution (RCE). This feature has been disabled by default for all installations from v2.33.8 onwards, including for existent installations.
Deeper analysisAI
CVE-2026-35585 is an OS command injection vulnerability in the hook system of File Browser, a file managing interface for uploading, deleting, previewing, renaming, and editing files within a specified directory. Affecting versions 2.0.0 through 2.63.1, the issue arises because administrator-defined shell commands executed on file events such as upload, rename, and delete perform variable substitution for values like $FILE and $USERNAME using os.Expand without sanitization. This allows shell metacharacters in filenames to inject and execute arbitrary commands. The vulnerability is rated 7.2 on the CVSS 3.1 scale (AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H) and maps to CWE-78 (Improper Neutralization of Special Elements used in an OS Command) and CWE-88 (Improper Neutralization of Argument Delimiters in a Command).
An attacker requires file write permissions, corresponding to the high privileges required (PR:H) in the CVSS score, to exploit this vulnerability. By crafting a malicious filename containing shell metacharacters and triggering a relevant file event like upload, rename, or delete, the attacker causes the server to execute arbitrary OS commands when the hook fires, resulting in remote code execution (RCE).
Advisories from the File Browser GitHub repository, including GHSA-jvpw-637p-h3pw and issue #5199, note that the hook feature has been disabled by default for all installations starting from version 2.33.8, including existing installations, as a mitigation measure.
Details
- CWE(s)