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

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2026-17545: 0.37% estimated exploitation activity in the next 30 days; percentile 30.69 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

1 Oct 2026, 09:29 UTC

Last modified by the source

26 Oct 2026, 08:45 UTC

Source last checked

26 Oct 2026, 12:50 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from osv record BIT-php-min-2026-17545

2. Revision 2 · amended · 26 Oct 2026

   Amended from osv record BIT-php-2026-17545

3. Revision 1 · created · 26 Oct 2026

   Published from osv record BIT-libphp-2026-17545

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# Patch Next advisory brief: CVE-2026-17545

Advisory: PHP on Windows: Reserved Device Names Are Not Rejected Before File/Stream I/O which can cause DoS
IDs: CVE-2026-17545
Record: https://patchnext.com/advisories/cve-2026-17545 (revision 3, source checked 26 Oct 2026, 12:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: php 8.5.11, 8.4.26, 8.3.35, 8.2.34; libphp 8.5.11, 8.4.26, 8.3.35, 8.2.34; php-min 8.5.11, 8.4.26, 8.3.35, 8.2.34. A vendor fix does not mean a deployment is fixed.

## Affected components
- Bitnami php: affected >= 8.2.0, < 8.2.34; >= 8.3.0, < 8.3.35; >= 8.4.0, < 8.4.26; >= 8.5.0, < 8.5.11; fixed in 8.3.35, 8.5.11, 8.4.26, 8.2.34
- Bitnami libphp: affected >= 8.2.0, < 8.2.34; >= 8.3.0, < 8.3.35; >= 8.4.0, < 8.4.26; >= 8.5.0, < 8.5.11; fixed in 8.3.35, 8.5.11, 8.4.26, 8.2.34
- Bitnami php-min: affected >= 8.2.0, < 8.2.34; >= 8.3.0, < 8.3.35; >= 8.4.0, < 8.4.26; >= 8.5.0, < 8.5.11; fixed in 8.3.35, 8.5.11, 8.4.26, 8.2.34

## Suggested inspection (read-only)
- Bitnami php: check the installed version with your package manager.
- Bitnami libphp: check the installed version with your package manager.
- Bitnami php-min: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on php, libphp, php-min.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/BIT-libphp-2026-17545 (OSV record BIT-libphp-2026-17545 lists affected ranges: Bitnami libphp >=8.2.0 =8.3.0 =8.4.0 =8.5.0 <8.5.11 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-php-2026-17545 (OSV record BIT-php-2026-17545 lists affected ranges: Bitnami php >=8.2.0 =8.3.0 =8.4.0 =8.5.0 <8.5.11 (fixed))
- Verified: https://osv.dev/vulnerability/BIT-php-min-2026-17545 (OSV record BIT-php-min-2026-17545 lists affected ranges: Bitnami php-min >=8.2.0 =8.3.0 =8.4.0 =8.5.0 <8.5.11 (fixed))

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