CVE-2026-17545: PHP Group PHP

Medium severity, CVSS 6.9. EPSS: 0.3% chance of exploitation in the next 30 days.

On Windows, PHP's filesystem and stream APIs do not reject reserved device names such as CON, PRN, AUX, NUL, COM1 to COM9, LPT1 to LPT9, CONIN$ and CONOUT$ when they appear as a component of a path. An attacker-controlled filename therefore reaches CreateFileW() and opens a device instead of the regular file the application expected, which can block or hang the request and exhaust worker processes.

Affected products

• PHP Group PHP: from 8.2, before 8.2.34 (fixed in 8.2.34); from 8.3, before 8.3.35 (fixed in 8.3.35); from 8.4, before 8.4.26 (fixed in 8.4.26); from 8.5, before 8.5.11 (fixed in 8.5.11)

Published 2026-09-25. Last modified 2026-09-29.