CVE-2026-27558 Overview
CVE-2026-27558 is a command injection vulnerability [CWE-78] affecting the /index.php/attached_devices_tab/ajax_remove_uploaded_iodd_files endpoint. A low-privileged remote attacker with operator credentials can inject operating system commands through this endpoint. Successful exploitation results in command execution with root privileges on the target device.
The flaw was disclosed through CERT VDE advisories VDE-2026-014, VDE-2026-027, and VDE-2026-028. The vulnerability enables full compromise of confidentiality, integrity, and availability from a network position.
Critical Impact
Authenticated operators can escalate to root through a single vulnerable web endpoint, giving attackers complete control over the affected device.
Affected Products
- Devices exposing the vulnerable ajax_remove_uploaded_iodd_files PHP endpoint (see CERT VDE advisories)
- Products covered under CERT VDE Advisory VDE-2026-014
- Products covered under CERT VDE Advisories VDE-2026-027 and VDE-2026-028
Discovery Timeline
- 2026-09-16 - CVE-2026-27558 published to the National Vulnerability Database
- 2026-09-16 - Last updated in NVD database
Technical Details for CVE-2026-27558
Vulnerability Analysis
The vulnerability resides in the PHP handler at /index.php/attached_devices_tab/ajax_remove_uploaded_iodd_files. This endpoint processes AJAX requests to remove uploaded iodd files from the device. Instead of sanitizing user input, the handler passes request parameters into an operating system command executed by a privileged backend process.
Because the underlying service runs as root, injected commands inherit root privileges. Authentication is required, but the operator role is a low-privilege tier intended for routine device management. This mismatch between the caller's assigned role and the resulting execution context enables vertical privilege escalation.
Exploitation requires only network reachability to the management interface and valid operator credentials. The attacker does not need user interaction or physical access to the device.
Root Cause
The root cause is improper neutralization of special elements used in an OS command, classified as [CWE-78]. Parameters supplied to the file-removal endpoint are concatenated into a shell command without validation, quoting, or use of a safe execution API. Shell metacharacters such as ;, |, &&, and backticks pass through unchecked, allowing arbitrary command chaining.
Attack Vector
An attacker authenticates to the web management interface using operator credentials, then issues a crafted HTTP request to the vulnerable endpoint. The malicious payload is embedded in the parameter identifying the iodd file to be removed. When the backend constructs and executes the shell command, the injected payload runs alongside the intended command with root privileges.
The endpoint is reachable over the network, so exploitation does not require local access. Consult the CERT VDE advisories VDE-2026-014, VDE-2026-027, and VDE-2026-028 for vendor-specific technical details.
Detection Methods for CVE-2026-27558
Indicators of Compromise
- HTTP POST requests to /index.php/attached_devices_tab/ajax_remove_uploaded_iodd_files containing shell metacharacters such as ;, |, &, $(, or backticks in request parameters.
- Unexpected child processes spawned by the web server user or PHP handler, particularly shells such as /bin/sh, bash, or utilities like wget, curl, nc, or busybox.
- New root-owned files, cron entries, or SSH authorized_keys modifications appearing shortly after authenticated operator sessions.
Detection Strategies
- Inspect web server access logs for requests to the vulnerable endpoint containing URL-encoded shell metacharacters or unusually long parameter values.
- Correlate authenticated operator sessions with process execution events on the device to identify command chains that deviate from normal file-removal behavior.
- Deploy signatures on network sensors that flag HTTP requests to the ajax_remove_uploaded_iodd_files path containing suspicious characters.
Monitoring Recommendations
- Continuously monitor administrative interfaces of affected devices for anomalous authentication patterns from operator accounts.
- Alert on outbound network connections initiated by the device to unknown hosts following administrative HTTP activity.
- Baseline expected process trees for the web management stack and alert on deviations such as shell interpreters spawned from PHP.
How to Mitigate CVE-2026-27558
Immediate Actions Required
- Apply vendor patches referenced in CERT VDE advisories VDE-2026-014, VDE-2026-027, and VDE-2026-028 as soon as they are available for your product.
- Restrict network access to the device management interface using firewall rules or a dedicated management VLAN.
- Rotate all operator credentials and audit account inventories for unused or shared accounts.
Patch Information
Refer to the CERT VDE advisories for the current patch status and fixed firmware versions applicable to each affected product family. Verify the installed version after patching and confirm the vulnerable endpoint no longer accepts unsanitized input.
Workarounds
- Block access to /index.php/attached_devices_tab/ajax_remove_uploaded_iodd_files at an upstream reverse proxy or web application firewall until patches are deployed.
- Limit operator accounts to trusted personnel and enforce strong, unique passwords with multi-factor authentication where supported.
- Place affected devices behind a jump host and disable direct network exposure of the management interface to untrusted networks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.