CVE-2025-66398

Summary

Summary An unauthenticated attacker can pollute the internal state (restoreFilePath) of the server via the /skServer/validateBackup endpoint. This allows the attacker to hijack the administrator's "Restore" functionality to overwrite critical server configuration files (e.g., security.json, package.json), leading to account takeover and Remote Code Execution (RCE). Details The vulnerability is caused by the use of a module-level global variable restoreFilePath in src/serverroutes.ts, which is shared across all requests. Vulnerable Code Analysis: Global State: restoreFilePath is defined at the top level of the module. typescript // src/serverroutes.ts let restoreFilePath: string Unauthenticated State Pollution: The /skServer/validateBackup endpoint updates this variable. Crucially, this endpoint lacks authentication middleware, allowing any user to access it. typescript app.post(${SERVERROUTESPREFIX}/validateBackup, (req, res) => { // ... handles file upload ... restoreFilePath = fs.mkdtempSync(...) // Attacker controls this path }) Restore Hijacking: The /skServer/restore endpoint uses the polluted restoreFilePath to perform the restoration. typescript app.post(${SERVERROUTESPREFIX}/restore, (req, res) => { // ... const unzipStream = unzipper.Extract({ path: restoreFilePath }) // Uses polluted path // ... }) Exploit Chain: Pollution: Attacker uploads a malicious zip file to /validateBackup. The server saves it and updates restoreFilePath to point to this malicious file. Hijacking: When /restore is triggered (either by the attacker if they have access, or by a legitimate admin), the server restores the attacker's malicious files. Backdoor: The attacker overwrites security.json to add a new administrator account. RCE: Using the new admin account, the attacker exploits a separate Command Injection vulnerability in the App Store (/skServer/appstore/install/...) to execute arbitrary system commands (e.g., npm install injection). PoC Here is a complete Python script to reproduce the full exploit chain. Impact Remote Code Execution (RCE), Account Takeover, Denial of Service. Verified: RCE is demonstrated by creating a file named rceproof.txt containing the text "RCESUCCESS" on the server filesystem using the exploit chain.

Impact

Affected versions

Security releases

Remediation advice