A code injection flaw exists in Buffalo Wi‑Fi router products that lets an attacker execute arbitrary commands on the device. The vulnerability arises from insufficient validation of user‑supplied input in the firmware, allowing malicious code to bypass normal controls. If exploited, the attacker would gain full control of the router, potentially intercepting or manipulating traffic, altering routing tables, and installing persistent malware that could affect all devices on the network.

The flaw impacts a broad selection of Buffalo Wi‑Fi router models, including FS‑M1266, FS‑S1266, VR‑U300W, VR‑U500X, WAPM‑1266R, WAPM‑1266WDPR, WAPM‑1266WD PRA, WAPM‑1750D, WAPM‑2133R, WAPM‑2133TR, WAPM‑AX4R, WAPM‑AX8R, WAPM‑AXETR, WAPS‑1266, WAPS‑AX4, WCR‑1166DHPL, WEM‑1266, WEM‑1266WP, WRM‑D2133HP, WRM‑D2133HS, WSR3600BE4KH, WSR3600BE4P, WTR‑M2133HP, WTR‑2133HS, WX‑R‑1750DHP2, WX‑R‑1750DHP, WX‑R‑1900DHP2, WX‑R‑1900DHP3, WX‑R‑1900DHP, WX‑R‑5950AX12, WX‑R‑6000AX12B, WX‑R‑6000AX12P, WX‑R‑6000AX12S, WX‑R18000BE10P, WZR‑1166DHP2, WZR‑1166DHP, WZR‑1750DHP2, WZR‑1750DHP, WZR‑600DHP2, WZR‑600DHP3, WZR‑600DHP, WZR‑900DHP2, WZR‑900DHP, WZR‑S1750DHP, WZR‑S600DHP, and WZR‑S900DHP. All firmware versions indicated by the listed CPEs are affected; the exact firmware revision that resolves the issue is specified in Buffalo’s update announcement.

The vulnerability carries a high severity rating of 8.7 according to CVSS, but recent probability metrics show an EPSS score of less than 1%. It is not catalogued in the national Known Exploited Vulnerabilities database. The likely attack vector is remote through the router’s web management interface or firmware upload path, as it involves processing of data supplied by users during configuration. Based on the description, it is inferred that an attacker could submit malicious input from any network connected to the router. A successful exploit would grant the attacker administrative control, enabling the creation of backdoors, data exfiltration, or further lateral movement within the local network.