All vulnerabilities
CVE-2026-17545GHSA-9f67-6fw4-hpfp

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

PHP Group PHPRuntimes & languages
Open in ThreatlineRecord JSON
CVSS
6.9Medium
ExploitationPublic exploit codeCISA's assessment says proof of concept code is public, assessed 25 Sep 2026. Not in the KEV catalogCISA via CVE List
Exploit odds (EPSS)0.32%Chance of exploitation activity in the next 30 days, higher than 24% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in8.2.34Also 8.3.35, 8.4.26 and 1 moreCVE List
Published25 Sep 2026Updated 25 Sep 2026CVE List

What fixes it

Show all 8 fixed versions

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

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.

Text from CVE List

Affected versions 8

  • PHPaffected: 8.2.* before 8.2.34CVE List
  • PHPaffected: 8.3.* before 8.3.35CVE List
  • PHPaffected: 8.4.* before 8.4.26CVE List
  • PHPaffected: 8.5.* before 8.5.11CVE List
  • php-src, other<8.2.34GitHub
  • php-src, other<8.3.35GitHub
  • php-src, other<8.4.26GitHub
  • php-src, other<8.5.11GitHub

References 1