CVE-2026-15543 Overview
CVE-2026-15543 is a buffer overflow vulnerability in the Tenda CH22 router running firmware version 1.0.0.1. The flaw resides in the formCertListInfo function handling requests to the /goform/CertListInfo endpoint. Attackers can trigger the overflow by manipulating the Name argument in HTTP requests to the router's web interface. The vulnerability is remotely exploitable across the network and requires low privileges. A public exploit has been released, increasing the risk of opportunistic attacks against exposed devices. The weakness is classified under [CWE-119] for improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers can corrupt memory on affected Tenda CH22 routers through crafted Name parameters, potentially leading to arbitrary code execution or denial of service.
Affected Products
- Tenda CH22 router, firmware version 1.0.0.1
- /goform/CertListInfo web management endpoint
- formCertListInfo request handler function
Discovery Timeline
- 2026-07-13 - CVE-2026-15543 published to NVD
- 2026-07-13 - Last updated in NVD database
Technical Details for CVE-2026-15543
Vulnerability Analysis
The vulnerability exists in the formCertListInfo function, which processes certificate listing operations exposed through the /goform/CertListInfo URI on the Tenda CH22 router's HTTP administration interface. The function accepts a Name parameter from user-supplied input and copies it into a fixed-size buffer without validating its length. When the input exceeds the destination buffer size, adjacent memory is overwritten, resulting in a classic buffer overflow condition. Successful exploitation can corrupt the stack or heap, disrupt device operation, or enable execution of attacker-controlled code. According to the CVE record, a working exploit is publicly available, which lowers the barrier for attackers targeting exposed CH22 devices. The current EPSS probability is 0.466%.
Root Cause
The root cause is the absence of bounds checking when the formCertListInfo handler copies the Name argument into a fixed-length buffer. Tenda's firmware relies on unsafe string operations that trust the client-provided length, a common pattern in embedded router code paths mapped under /goform/. This maps to [CWE-119], improper restriction of operations within the bounds of a memory buffer.
Attack Vector
Exploitation requires network access to the device's HTTP management interface and a valid low-privilege session. An attacker sends a crafted POST or GET request to /goform/CertListInfo with an oversized Name parameter. Devices with the web interface exposed to the internet or accessible from untrusted network segments face the highest risk. No user interaction is required. Refer to the VulDB CVE-2026-15543 entry and the technical write-up on Notion for reproduction details.
No verified proof-of-concept code is included here; see the linked technical references for exploitation specifics.
Detection Methods for CVE-2026-15543
Indicators of Compromise
- HTTP requests to /goform/CertListInfo containing unusually long Name parameter values.
- Unexpected reboots, crashes, or watchdog resets on Tenda CH22 devices following inbound web traffic.
- New or unexplained outbound connections originating from the router after receiving suspicious HTTP requests.
Detection Strategies
- Inspect web application firewall (WAF) or IDS/IPS logs for POST or GET requests to /goform/CertListInfo with parameter lengths exceeding typical values.
- Correlate router syslog crash events with preceding HTTP traffic to the management interface.
- Deploy network signatures matching oversized Name= payloads targeting the formCertListInfo handler.
Monitoring Recommendations
- Monitor administrative interfaces of Tenda CH22 devices for unauthenticated or brute-force login attempts.
- Log and alert on any external-source access to router management ports (typically TCP/80 or TCP/443).
- Track firmware integrity and configuration changes on network gateway devices.
How to Mitigate CVE-2026-15543
Immediate Actions Required
- Restrict access to the Tenda CH22 management interface to trusted internal networks only, blocking WAN-side administration.
- Change default and shared administrator credentials to reduce the risk of low-privilege attackers reaching the vulnerable endpoint.
- Segment CH22 routers away from sensitive assets until a vendor patch is applied.
- Review router logs for signs of prior exploitation attempts against /goform/CertListInfo.
Patch Information
At the time of publication, no vendor patch has been referenced in the NVD entry. Consult the Tenda official website for firmware updates and the VulDB vulnerability record #377893 for tracking remediation status.
Workarounds
- Disable remote web administration on the CH22 device.
- Place the router behind an upstream firewall that filters inbound HTTP requests to /goform/CertListInfo.
- Where feasible, replace end-of-support or unpatched CH22 units with actively maintained hardware.
# Example ACL to block external access to the router management interface
iptables -A INPUT -p tcp --dport 80 -i wan0 -j DROP
iptables -A INPUT -p tcp --dport 443 -i wan0 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
