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Public proof of conceptFix available

CVE-2026-17545

A public proof of concept exists; no exploitation attested.

  • Published2026-09-25
  • Fixed in8.5.11 · 8.4.26 · 8.3.35 · 8.2.34
  • WeaknessCWE-67

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2026-09-2521:17CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-17545?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-17545?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV
PHPversion to verify
BranchAffectedFixed in
8.5≥ 8.5.0, < 8.5.118.5.11
8.4≥ 8.4.0, < 8.4.268.4.26
8.3≥ 8.3.0, < 8.3.358.3.35
8.2≥ 8.2.0, < 8.2.348.2.34

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2026-17545 Red Hat Product Security57 products fixed

    php: PHP: Denial of Service via reserved device names on Windows

  • RHSA-2026:70720 Red Hat Product Security57 products fixed

    Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Full record on NVD

Fix

  1. Update PHP to 8.5.11 · 8.4.26 · 8.3.35 · 8.2.34
  2. Vendor fix Red Hat Product Security CVE-2026-17545 · 57 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
  3. Workaround from the vendor Red Hat Product Security CVE-2026-17545 · 57 productsNo action is required for Red Hat Enterprise Linux or other Linux-based Red Hat products, which do not implement Windows reserved device-name handling. On Windows PHP deployments, upgrade to a fixed PHP release and reject user-controlled path components that resolve to reserved device names.

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • CISA-ADPSSVC decisionpoc2026-09-25
  • OpenCVESSVC decisionpoc—
  • CNACVSS 4.06.9read 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CNAweakness (CWE)CWE-67read 2026-10-23
  • FIRST EPSSEPSS score0.3 %2026-10-22
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
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/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
Published
2026-09-25
Last Modified
2026-10-23
NVD status
Analyzed

Frequently asked questions

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.

Is CVE-2026-17545 actively exploited?

A proof-of-concept exploit exists for CVE-2026-17545, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2026-17545?

CVE-2026-17545 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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