CVE-2018-17015
Description
An issue was discovered on TP-Link TL-WR886N 6.0 2.3.4 and TL-WR886N 7.0 1.1.0 devices. Authenticated attackers can crash router services (e.g., inetd, HTTP, DNS, and UPnP) via long JSON data for ddns phddns username.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Authenticated attackers can crash TP-Link TL-WR886N router services (inetd, HTTP, DNS, UPnP) by sending a long JSON value for the DDNS phddns username.
Vulnerability
An issue exists in the DDNS module of TP-Link TL-WR886N routers running firmware versions 6.0 2.3.4 and 7.0 1.1.0. Sending a crafted HTTP POST request with an excessively long value for the phddns username in JSON format causes a buffer overflow that corrupts the DDNS configuration file and subsequently crashes the inetd task, which manages multiple network services [1].
Exploitation
An attacker must have authenticated access to the router's web interface. Using a script similar to the provided proof of concept, the attacker sends a POST request to the DDNS endpoint with a long string in the phddns username field. The overflow triggers a crash in the inetd process, leading to a denial of service [1].
Impact
Successful exploitation causes the inetd task to crash, stopping critical network services such as HTTP (web interface), DNS, and UPnP. This results in a denial of service, preventing legitimate users from accessing router management or using DNS and other services [1].
Mitigation
No official fix has been released by TP-Link as of the publication date (2018-09-13). The only mitigation is to restrict access to the router's administration interface to trusted users and ensure the device is not exposed to untrusted networks. Users should monitor for firmware updates from the vendor [1].
AI Insight generated on May 26, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
1Patches
0No patches discovered yet.
Vulnerability mechanics
Root cause
"Missing input-length validation on the `phddns.username` JSON field allows a buffer overflow when the value is written to the DDNS config file."
Attack vector
An authenticated attacker sends an HTTP POST request to the router's `/stok=
Affected code
The vulnerability resides in the DDNS module of the TP-Link TL-WR886N firmware (version 1.1.0 for hardware v7.0). The module processes a JSON key `phddns.username` without enforcing a length limit, and the oversized value is written into a config file, eventually overflowing a buffer and crashing the `inetd` task [ref_id=1].
What the fix does
No patch is provided in the bundle. The advisory [ref_id=1] does not describe any vendor fix; it only documents the crash condition. To remediate, the DDNS module should validate the length of the `phddns.username` field before writing it to the config file, and the underlying buffer should be sized appropriately to prevent overflow.
Preconditions
- authAttacker must have valid credentials to authenticate to the router's web interface.
- networkAttacker must be able to reach the router's HTTP management interface (typically on the LAN).
- inputThe attacker sends a crafted JSON payload with an excessively long `username` value (e.g., ~1.5 MB of 'A' characters).
Reproduction
The PoC in [ref_id=1] demonstrates reproduction: authenticate to the router, then POST a JSON body to `/stok=
Generated on May 26, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
1News mentions
0No linked articles in our index yet.