CVE-2026-9513 Overview
CVE-2026-9513 is an OS command injection vulnerability in the Totolink CA750-PoE router running firmware version 6.2c.510. The flaw resides in the NTPSyncWithHost function within /cgi-bin/cstecgi.cgi, part of the Setting Handler component. Attackers can manipulate the host_time parameter to inject and execute arbitrary operating system commands. The issue is exploitable remotely, and a public exploit has been disclosed. The vulnerability is tracked under [CWE-77] (Improper Neutralization of Special Elements used in a Command).
Critical Impact
Authenticated remote attackers can execute arbitrary OS commands on the router by injecting payloads into the host_time argument of the NTPSyncWithHost handler.
Affected Products
- Totolink CA750-PoE firmware version 6.2c.510
- Component: Setting Handler (/cgi-bin/cstecgi.cgi)
- Function: NTPSyncWithHost
Discovery Timeline
- 2026-05-25 - CVE-2026-9513 published to NVD
- 2026-05-26 - Last updated in NVD database
Technical Details for CVE-2026-9513
Vulnerability Analysis
The vulnerability exists in the CGI binary cstecgi.cgi, which handles configuration requests on the Totolink CA750-PoE device. When a request invokes the NTPSyncWithHost action, the handler reads the host_time parameter from the request body and passes it to a system shell without proper neutralization of shell metacharacters. This allows an attacker to append additional commands using shell separators such as ;, &&, or backticks. The injected commands run with the privileges of the CGI process, typically root on embedded routers. Successful exploitation enables full device compromise, credential theft, configuration tampering, and lateral movement within the network.
Root Cause
The root cause is insufficient input sanitization in the NTPSyncWithHost function. User-controlled data from the host_time argument is concatenated into a command string and dispatched to a shell interpreter. No allow-listing, escaping, or argument-vector execution is performed, which classifies the flaw under [CWE-77].
Attack Vector
Exploitation requires network reachability to the CGI endpoint and low-privilege access to submit a crafted HTTP request to /cgi-bin/cstecgi.cgi. The attacker sends a POST request invoking the NTPSyncWithHost action with a host_time value containing shell metacharacters and a follow-on command. Public proof-of-concept material is referenced in the GitHub Vulnerability Documentation and the VulDB #365513 advisory.
Detection Methods for CVE-2026-9513
Indicators of Compromise
- HTTP POST requests to /cgi-bin/cstecgi.cgi containing the NTPSyncWithHost action with shell metacharacters (;, |, &, `, $()) in the host_time parameter.
- Unexpected outbound connections from the router to attacker-controlled infrastructure following NTP-related configuration requests.
- New or modified processes spawned by the CGI handler that are not part of normal NTP synchronization activity.
Detection Strategies
- Inspect web server and reverse proxy logs for requests targeting cstecgi.cgi with anomalous host_time values.
- Apply intrusion detection signatures that flag command-injection patterns in HTTP parameters destined for embedded device management interfaces.
- Correlate router management traffic with downstream endpoint telemetry to identify post-exploitation behavior such as scanning or credential harvesting.
Monitoring Recommendations
- Capture and centralize syslog and HTTP access logs from the CA750-PoE in a SIEM for retrospective analysis.
- Monitor authentication events to the device administration interface and alert on logins from unexpected source addresses.
- Track changes in NTP configuration and other Setting Handler operations that occur outside scheduled maintenance windows.
How to Mitigate CVE-2026-9513
Immediate Actions Required
- Restrict access to the CA750-PoE management interface to trusted administrative networks using firewall rules or ACLs.
- Disable remote (WAN-side) administration of the device until a vendor patch is available.
- Rotate administrative credentials and audit existing user accounts for unauthorized additions.
- Review device logs for prior exploitation attempts referencing NTPSyncWithHost or host_time.
Patch Information
No vendor patch is referenced in the published advisory at the time of disclosure. Consult the Totolink Official Website for firmware updates beyond 6.2c.510 and apply them promptly when released. Additional technical context is available in the VulDB #365513 CTI entry.
Workarounds
- Place the device behind a network segment that blocks untrusted hosts from reaching /cgi-bin/cstecgi.cgi.
- Enforce VPN-only access for any administrative functions exposed by the router.
- If the device is not actively used in production, decommission it or replace it with a model that receives current security updates.
# Example: restrict management interface to a trusted subnet using iptables on an upstream gateway
iptables -A FORWARD -p tcp -d <CA750-PoE-IP> --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <CA750-PoE-IP> --dport 80 -j DROP
iptables -A FORWARD -p tcp -d <CA750-PoE-IP> --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A FORWARD -p tcp -d <CA750-PoE-IP> --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
