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CVE-2026-17545

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

Medium6.9EPSS 0.37%
Published
Updated
Reserved
Assigned by
php

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.

Scores

CVSS scores of CVE-2026-17545, by who scored it
Scored byCVSSScoreVector
phpCNA (assigner)4.0Medium6.9CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:H
NVDNVD · Analyzed4.0Medium6.9CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (exploitation in 30 days)
0.37% · top 69% of all CVEs (6 Nov 2026)
CISA SSVC
Exploitation: poc · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.9.

Weakness

Affected products

  • PHP Group · PHP

    • affected 8.2.* – < 8.2.34
    • affected 8.3.* – < 8.3.35
    • affected 8.4.* – < 8.4.26
    • affected 8.5.* – < 8.5.11

References (1)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .