CVE-2026-71268 — CRITICAL (9.9)

Vulnerability Description

OpenPLC Runtime v3's compile_program() function (webserver/openplc.py) parses `(*FILE:path content*)` directives from uploaded Structured Text (.st) program files and writes the referenced content to `os.path.join('./core', file_path)` with no validation that file_path stays within the ./core directory. A crafted .st file containing a directive such as `(*FILE:../../../etc/cron.d/x * * * * root <command>*)` writes attacker-controlled content to an arbitrary filesystem path, enabling remote code execution (e.g. via cron or SSH authorized_keys). A path-validation function, validate_file_path(), exists elsewhere in the codebase (webserver/credentials.py) but is never invoked from compile_program(), leaving the sink unprotected. OpenPLC additionally ships with hardcoded default credentials (openplc:openplc), lowering the practical bar for exploitation.

CVSS Score

9.9

CRITICAL

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-22

References

FAQ

What is CVE-2026-71268?

CVE-2026-71268 is a vulnerability with a CVSS score of 9.9 (CRITICAL). OpenPLC Runtime v3's compile_program() function (webserver/openplc.py) parses `(*FILE:path content*)` directives from uploaded Structured Text (.st) program files and writes the referenced content to ...

How severe is CVE-2026-71268?

CVE-2026-71268 has been rated CRITICAL with a CVSS base score of 9.9/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-71268?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.