CVE-2026-14480
CriticalCVSS 9.9Exploitation Probability (EPSS)
Low risk45th percentile - higher than 45% of all known CVEs
Summary
OpenPLC Runtime v3 has an authenticated arbitrary file write vulnerability in the legacy web UI program upload workflow. An attacker can supply an arbitrary filename stored in the database and used as the destination path without validation, allowing file writes anywhere writable by the webserver process.
Risk Assessment
The risk is the potential escalation of arbitrary file write to arbitrary native code execution by placing a malicious .cpp file in the OpenPLC runtime core directory, which is automatically compiled into the executable binary during normal program compilation.
Recommendation
Immediately update OpenPLC Runtime to the latest version that fixes this vulnerability and restrict access to the web UI to trusted users only.
Other vulnerabilities in OpenPLC Runtime
See all- CVE-2026-71268Critical
OpenPLC Runtime v3's compile_program function parses directives from uploaded Structured Text (.st) files and writes referenced content without validating that the file path stays within the ./core directory. A path-validation function exists but is never invoked from compile_program.
- CVE-2025-34226High
OpenPLC Runtime v3 contains an input validation flaw in the /upload-program-action endpoint: the epoch_time field supplied during program uploads is not validated and can be crafted to induce corruption of the programs database. After a successful malformed upload the runtime continues to operate until a restart; on restart the runtime can fail to start because of corrupted database entries, resulting in persistent denial of service requiring complete rebase of the product to recover. This vulnerability was remediated by commit 095ee09.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS