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CVE-2026-17545mediumCWE-67

PHP on Windows: Reserved Device Names Are Not Rejected Before File/Stream I/O which can cause DoS

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.9epss 0.3%
exploitation probability
0.3%top 77% of all CVEs
observed exploitation
nono source reports it
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.
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:H
Affected products
PHP Group · PHP