thiagoralves OpenPLC Structured Text File webserver/openplc.py compile_program file_path path traversal

Summaryinfo

A vulnerability, which was classified as very critical, was found in thiagoralves OpenPLC. This issue affects the function compile_program of the file webserver/openplc.py of the component Structured Text File Handler. Such manipulation of the argument file_path leads to path traversal. This vulnerability is uniquely identified as CVE-2026-71268. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as very critical, has been found in thiagoralves OpenPLC (affected version not known). Affected by this issue is the function compile_program of the file webserver/openplc.py of the component Structured Text File Handler. The manipulation of the argument file_path with an unknown input leads to a path traversal vulnerability. Using CWE to declare the problem leads to CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Impacted is confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-71268 since 08/05/2026. The exploitation is known to be easy. The attack may be launched remotely. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/05/2026). The MITRE ATT&CK project declares the attack technique as T1006.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

• thiagoralves

Name

• OpenPLC

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Discussion