This vulnerability resides in the pypdftk library (versions up to 0.5). The functions fill_form(), dump_data_fields(), and pdftk_cmd_util() construct shell commands from input paths supplied by the caller. If an attacker can control the pdf_path or out_file parameters, they can inject shell metacharacters that are interpreted by subprocess.Popen with shell=True, allowing execution of arbitrary OS commands as the user running the Python process. This is a classic operating‑system command‑injection flaw (CWE‑78).

The affected product is pypdftk distributed by revolunet, version 0.5 and earlier. No patch status is documented; the repository references a pull request that presumably contains the fix.

The severity is high, with a CVSS score of 9.3 and an EPSS score of 2%, indicating a low but non‑zero probability of exploitation in the field. The vulnerability is not listed in CISA KEV. Exploitation requires the ability to supply crafted pdf_path or out_file values to the library; it can be abused during normal execution of the pypdftk command or within scripts that import the library. An attacker who can trigger the vulnerable code under a privileged user can achieve full system compromise, while exploitation under a low‑privilege account gives the attacker the same privileges as that account.