What is CVE-2026-27650?

CVE-2026-27650 is a critical-severity vulnerability in Buffalo Fs-M1266, classified under OS Command Injection. CVSS score: 9.8/10. Published 2026-03-27.

How severe is CVE-2026-27650?

Critical severity. CVSS v3 base score is 9.8 out of 10.

RCE in Buffalo Fs-M1266

CVE-2026-27650

OS Command Injection vulnerability exists in BUFFALO Wi-Fi router products. If this vulnerability is exploited, an arbitrary OS command may be executed on the products.

Vulnerability class: Command Injection (OS Command Injection)

EPSS: 0.009 (56.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Buffalo Fs-m1266
Buffalo Fs-m1266_firmware
Buffalo Fs-s1266
Buffalo Fs-s1266_firmware
Buffalo Vr-u300w
Buffalo Vr-u300w_firmware
Buffalo Vr-u500x
Buffalo Vr-u500x_firmware
Buffalo Wapm-1266r
Buffalo Wapm-1266r_firmware

Weakness classification (CWE)

CWE-78 — OS Command Injection

References

vultures@jpcert.or.jp (Vendor Advisory)
vultures@jpcert.or.jp (Third Party Advisory)

Frequently asked questions

What is CVE-2026-27650?: CVE-2026-27650 is a critical-severity vulnerability in Buffalo Fs-M1266, classified under OS Command Injection. CVSS score: 9.8/10. Published 2026-03-27.
How severe is CVE-2026-27650?: Critical severity. CVSS v3 base score is 9.8 out of 10.