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CWE-73Weakness · CWE-73

CVE-2026-14480

CRITICAL · 9.9 CVSS v3.1 Published 2026-07-10
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable Zero-click 6 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
OpenPLC Runtime v3 contains an authenticated arbitrary file write vulnerability in the legacy web UI program‑upload workflow. The application stores an attacker‑supplied filename (prog_file) directly into the Programs.File database field and later uses this value as the destination path for an uploaded file without validating or restricting the path. Because Python os.path.join() honors attacker‑controlled absolute paths, an authenticated user can write arbitrary files anywhere writable by the OpenPLC webserver process. In the default build pipeline, all C++ source files within the OpenPLC runtime core directory are automatically compiled into the executable runtime binary. By writing a malicious .cpp file into this directory, an authenticated attacker can escalate the arbitrary file write into arbitrary native code execution when the operator triggers a normal program compilation and runtime start.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

OpenPLC Runtime v3 has an authenticated arbitrary file write vulnerability in its legacy web UI program-upload workflow. The prog_file parameter is stored directly in the database and used as the destination path without validation, allowing os.path.join() to honor absolute paths for directory traversal. Since the default build pipeline automatically compiles any .cpp files in the runtime core directory into the executable, an authenticated attacker can write a malicious .cpp file and achieve arbitrary native code execution upon triggering normal program compilation.

MitigationImplement strict path validation on the prog_file parameter to restrict file writes to an approved directory and prevent path traversal. Additionally, exclude the runtime core directory from the auto-compilation build pipeline or implement allowlist validation for C++ files before compilation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify OpenPLC Runtime version
    Locate the installed OpenPLC Runtime binary or package and query its version information using the platform's standard package manager or runtime version command.
    Affected if The installed version is OpenPLC Runtime v3.x.
  2. Verify legacy web UI is accessible
    Check if the legacy web interface (typically on port 8080) is listening and responding. Attempt to access the program-upload endpoint with a test account.
    Affected if The legacy web UI is exposed and accepts authentication.
  3. Confirm program-upload functionality exists
    Locate the program upload workflow in the web interface and identify the prog_file parameter handling in the backend code or configuration.
    Affected if A program-upload feature exists that accepts a prog_file parameter.
  4. Inspect database storage of prog_file
    Examine the OpenPLC database for records containing the prog_file parameter values. Check if absolute paths or directory traversal sequences (such as ../) are stored directly without sanitization.
    Affected if The prog_file values are stored verbatim without path validation or normalization.
  5. Check runtime core directory for .cpp files
    Inspect the runtime core directory for any .cpp source files that could be written via the upload function and subsequently compiled.
    Affected if The runtime core directory contains .cpp files and permits write access from the web server process.

A user is affected if they run OpenPLC Runtime v3 with the legacy web UI enabled and the prog_file parameter in the program-upload workflow stores unsanitized paths that allow writing .cpp files to the runtime core directory.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement strict path validation on the prog_file parameter to restrict file writes to an approved directory and prevent path traversal. Additionally, exclude the runtime core directory from the auto-compilation build pipeline or implement allowlist validation for C++ files before compilation.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
28.0 hours of engineering $4,980
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-14480 in production — separate from our analysis above.

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What this is

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What belongs here
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