CVE-2026-110957 Overview
CVE-2026-110957 is an OS command injection vulnerability in the Wavlink WL-WN530BE2-A wireless router through firmware version M30BE2_V250604. The flaw resides in the sub_12580 function within api.cgi, which handles login processing. An unauthenticated remote attacker can manipulate the REMOTE_ADDR argument to inject arbitrary operating system commands [CWE-77]. The vendor confirmed the issue and released fixed firmware 2026-09-24-841a51c6d5_tclinux.bin, which replaces the vulnerable system() call with an argument-vector execvp() invocation and enforces length and null checks on the client address.
Critical Impact
Unauthenticated remote attackers can execute arbitrary OS commands on affected Wavlink routers, leading to full device compromise and pivoting into internal networks.
Affected Products
- Wavlink WL-WN530BE2-A router
- Firmware versions up to and including M30BE2_V250604
- api.cgi component (Login Processing, sub_12580 function)
Discovery Timeline
- 2026-10-15 - CVE-2026-110957 published to NVD
- 2026-10-20 - Last updated in NVD database
Technical Details for CVE-2026-110957
Vulnerability Analysis
The vulnerability exists in the sub_12580 function of api.cgi, which processes login requests on the api=info&client=app handler. The function constructs a shell command string that incorporates the REMOTE_ADDR value supplied by the HTTP client. Because the input is passed directly to system() without sanitization, shell metacharacters embedded in REMOTE_ADDR are interpreted by the underlying shell. This OS command injection path [CWE-77] runs with the privileges of the web server process, which typically operates as root on consumer-grade router firmware. The exploit has been publicly disclosed, increasing the likelihood of opportunistic scanning and automated exploitation across exposed devices.
Root Cause
The root cause is unsafe command construction. The login script was invoked through system() with the client address concatenated into a shell string, with no length limit and no null-byte validation. Any shell metacharacter supplied in REMOTE_ADDR becomes part of the executed command.
Attack Vector
The attack vector is network-based and requires no authentication or user interaction. An attacker sends a crafted HTTP request to the api.cgi endpoint with a malicious REMOTE_ADDR header value. The vulnerable handler passes the attacker-controlled string to the shell, executing injected commands on the device. See the GitHub CVE Documentation for the technical write-up and proof-of-concept details.
Stop Remote Code Execution Before It Runs
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Stop Exploit AttemptsDetection Methods for CVE-2026-110957
Indicators of Compromise
- Unusual HTTP requests to /cgi-bin/api.cgi containing shell metacharacters (;, |, `, $()) in headers that influence REMOTE_ADDR such as X-Forwarded-For or X-Real-IP.
- Unexpected outbound connections from the router to attacker-controlled hosts following login-related requests.
- New or modified binaries, cron entries, or startup scripts in the router filesystem after suspicious inbound HTTP traffic.
Detection Strategies
- Inspect web server and reverse-proxy logs in front of exposed Wavlink devices for anomalous REMOTE_ADDR-related header values containing non-IP characters.
- Monitor north-south network traffic for scans against api.cgi on routers running the WL-WN530BE2-A firmware line.
- Correlate inbound requests to the api=info&client=app handler with subsequent outbound DNS or TCP activity initiated by the router.
Monitoring Recommendations
- Collect router syslog and management-plane telemetry into a centralized SIEM for behavioral baselining.
- Alert on firmware version mismatches between deployed devices and the fixed build 2026-09-24-841a51c6d5_tclinux.bin.
- Track administrative interface exposure on perimeter firewalls and flag any Wavlink router with the management service reachable from the internet.
How to Mitigate CVE-2026-110957
Immediate Actions Required
- Upgrade all affected Wavlink WL-WN530BE2-A devices to firmware 2026-09-24-841a51c6d5_tclinux.bin or later from the official Wavlink Firmware Update download page.
- Remove direct internet exposure of the router administrative interface and restrict access to trusted management networks.
- Audit router configurations and credentials for signs of tampering after confirming patch status.
Patch Information
Wavlink confirmed the finding and released a corrected firmware image. In the patched build, the api=info&client=app handler no longer constructs a shell command. The login script is invoked through an argument vector using execvp() instead of system(), and the client address is both length-limited and null-checked. Reference the vendor-supplied binary at the Wavlink Firmware Update link and the advisory tracking at VulDB CVE-2026-110957.
Workarounds
- Block inbound access to api.cgi at an upstream firewall or ACL until the firmware upgrade is applied.
- Place vulnerable devices behind a reverse proxy that strips or normalizes X-Forwarded-For and related client-address headers.
- Segment affected routers from sensitive internal networks to limit lateral movement if exploitation occurs.
# Example upstream firewall rule to block external access to api.cgi
# Replace WAN_IF and ROUTER_IP with your environment values
iptables -I FORWARD -i WAN_IF -d ROUTER_IP -p tcp --dport 80 \
-m string --algo bm --string "/cgi-bin/api.cgi" -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
