CVE-2025-13258 Overview
CVE-2025-13258 is a buffer overflow vulnerability in the Tenda AC20 router firmware up to version 16.03.08.12. The flaw resides in an unknown function within the /goform/WifiExtraSet endpoint, where manipulation of the wpapsk_crypto argument triggers memory corruption. Attackers can exploit this issue remotely over the network with low-privilege authentication. Public exploit details are available, increasing the likelihood of opportunistic abuse against exposed devices. The weakness is classified under CWE-119, covering improper restriction of operations within the bounds of a memory buffer.
Critical Impact
Remote attackers with low privileges can corrupt memory on the device, potentially leading to denial of service or arbitrary code execution on affected Tenda AC20 routers.
Affected Products
- Tenda AC20 router (hardware)
- Tenda AC20 firmware versions up to and including 16.03.08.12
- Deployments exposing the web management interface to untrusted networks
Discovery Timeline
- 2025-11-17 - CVE-2025-13258 published to NVD
- 2025-11-19 - Last updated in NVD database
Technical Details for CVE-2025-13258
Vulnerability Analysis
The vulnerability exists in the HTTP request handler responsible for processing wireless configuration updates through the /goform/WifiExtraSet endpoint. When an authenticated client submits a request containing the wpapsk_crypto parameter, the firmware copies the attacker-controlled value into a fixed-size buffer without enforcing length validation. The resulting buffer overflow corrupts adjacent memory on the stack or heap of the embedded httpd process.
Because Tenda's embedded web server runs with elevated privileges on the device, successful memory corruption can crash the management daemon or alter execution flow. This vulnerability class is consistent with prior Tenda router flaws affecting goform endpoints, where parameter parsing relies on unsafe string copy operations.
Root Cause
The root cause is missing bounds checking on the wpapsk_crypto parameter inside the request handler. The handler treats the input as a trusted, length-bounded string and writes it into a fixed-size destination buffer. This pattern maps directly to [CWE-119] and typically involves unsafe functions such as strcpy or sprintf in MIPS-based firmware binaries.
Attack Vector
Exploitation requires network access to the router's web administration interface and valid low-privilege credentials. An attacker sends a crafted HTTP POST request to /goform/WifiExtraSet containing an oversized wpapsk_crypto value. The malformed request triggers the overflow during request parsing, with no user interaction required at the victim end. Devices exposing the management interface to the WAN or to untrusted internal segments are at highest risk.
The vulnerability mechanism and exploitation evidence are documented in the public proof-of-concept hosted on the GitHub PoC Repository and tracked as VulDB #332593.
Detection Methods for CVE-2025-13258
Indicators of Compromise
- HTTP POST requests to /goform/WifiExtraSet containing abnormally long wpapsk_crypto parameter values
- Unexpected restarts or crashes of the Tenda AC20 web management daemon (httpd)
- Configuration changes to wireless security settings that do not match authorized administrative activity
- Inbound traffic to the router management interface from untrusted source IPs
Detection Strategies
- Inspect web server access logs on the device, where available, for repeated POST requests to /goform/WifiExtraSet
- Deploy network IDS signatures that match oversized wpapsk_crypto parameter values in HTTP request bodies destined for Tenda routers
- Correlate router availability monitoring with HTTP request telemetry to identify crashes that align with suspicious POST traffic
Monitoring Recommendations
- Monitor north-south traffic to and from router management interfaces and alert on access from non-administrative subnets
- Track firmware version inventory across all deployed Tenda AC20 devices to identify unpatched units
- Forward router syslog data to a centralized logging platform and alert on repeated httpd restarts or authentication anomalies
How to Mitigate CVE-2025-13258
Immediate Actions Required
- Restrict access to the router's web management interface to trusted administrative hosts only, and disable WAN-side management
- Rotate administrative credentials on all Tenda AC20 devices to reduce the risk of low-privilege authenticated exploitation
- Segment vulnerable routers from sensitive network zones until a vendor patch is applied
- Monitor the Tenda official website for firmware updates addressing CVE-2025-13258
Patch Information
At the time of publication, no vendor-supplied firmware update addressing CVE-2025-13258 has been listed in the referenced advisories. Administrators should track the VulDB entry and the Tenda official website for an official fix. If an updated firmware version is released, apply it to all affected Tenda AC20 devices and validate the firmware build identifier after upgrade.
Workarounds
- Disable remote (WAN) administration on affected routers to eliminate internet-facing exposure of /goform/WifiExtraSet
- Enforce strict access control lists on the LAN side, allowing the management interface only from a dedicated administrative VLAN
- Replace end-of-life or unsupported Tenda AC20 hardware with actively maintained equipment if a vendor patch is not made available
- Place the router behind an upstream firewall that filters HTTP requests containing oversized parameter values to /goform/ endpoints
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
