What is CVE-2026-17545?
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.
The record classifies CVE-2026-17545 under weakness class CWE-67. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 49 days ago.
Severity and exploitation probability
- CVSS v4.0 base score
- 6.9 — Medium (derived from score)
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 - CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 3.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-09-25
Is CVE-2026-17545 being exploited?
No public exploitation evidence for CVE-2026-17545 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-09-25. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.
Affected products and versions
- PHP Group: PHP
How to fix CVE-2026-17545
Vendor advisory: https://github.com/php/php-src/security/advisories/GHSA-9f67-6fw4-hpfp. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-17545
1 tracked threat in the Threadlinqs corpus references CVE-2026-17545, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, NVD. This product uses the NVD API but is not endorsed or certified by the NVD.