PHP: Improper Handling of Windows Device Names
CVE-2026-17545 is a high-severity improper handling of windows device names vulnerability in PHP from PHP Group, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 8.2.34, 8.3.35, 8.4.26 as the first without the flaw, so updating PHP to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.37% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update PHP to 8.2.34 or 8.3.35 or 8.4.26 or 8.5.11, whichever matches your release line, or a later version.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| PHP Group | PHP | 8.2.* up to, but not including, 8.2.34; 8.3.* up to, but not including, 8.3.35; 8.4.* up to, but not including, 8.4.26; 8.5.* up to, but not including, 8.5.11 | 8.2.34, 8.3.35, 8.4.26, 8.5.11 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 6.9 | Medium | CNA (php.net) |
| CVSS 3.1 | 7.5 | High | NVD |
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Handling of Windows Device Names
The product constructs pathnames from user input, but it does not handle or incorrectly handles a pathname containing a Windows device name such as AUX or CON. This typically leads to denial of service or an information exposure when the application attempts to process the pathname as a regular file.
How developers prevent this class of flaw
- Be familiar with the device names in the operating system where your system is deployed. Check input for these device names.
More Improper Handling of Windows Device Names vulnerabilities (CWE-67)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in PHP
- 8.1 High severity
PHP Stale Internal Request-State Exploited
- 9.8 Critical severity
PHP Memory Corruption Exploited
- 7.5 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.5 High severity
Recent Improper Handling of Windows Device Names vulnerabilities
- 10.0 Critical severity
Spotted an error? Tell us.