---
id: CVE-2026-17545
title: >-
  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
summary: >-
  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 theref…
severity: medium
cvss: 6.9
cvssVector: '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'
cwe:
  - CWE-67
  - CWE-66
vendor: PHP Group
product: PHP
affected:
  - PHP >= 8.2.* < 8.2.34
  - PHP >= 8.3.* < 8.3.35
  - PHP >= 8.4.* < 8.4.26
  - PHP >= 8.5.* < 8.5.11
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T21:17:23.253'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-17545'
references:
  - url: 'https://github.com/php/php-src/security/advisories/GHSA-9f67-6fw4-hpfp'
    label: security@php.net
  - url: 'https://github.com/php/php-src/security/advisories/GHSA-9f67-6fw4-hpfp'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-17545.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-17545'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2541645'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-17545'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-17545'
  - url: 'https://access.redhat.com/errata/RHSA-2026:70720'
tags:
  - nvd
  - cve.org
  - exploit-available
  - csaf
  - vex
  - red-hat
exploitAvailable: true
ssvc:
  exploitation: poc
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-25T20:43:10.043800Z'
cvssSource: cna
ingestedAt: '2026-09-25T21:19:40.144Z'
patched:
  - hardened_images
scores:
  cna: 6.9
  vendor: 5.9
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **RHSA-2026:70720** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-23 · [advisory](https://access.redhat.com/errata/RHSA-2026:70720)
- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, … · updated 2026-09-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-17545.json)