RCE in Python Pillow
CVE-2026-55798
Pillow is a Python imaging library. Prior to 12.3.0, WindowsViewer.get_command() constructed a cmd.exe shell command by directly embedding a file path into an f-string without escaping and passed the result to subprocess.Popen(..., shell=True), allowing shell metacharacters in the file path to inject arbitrary cmd.exe commands. This issue is fixed in version 12.3.0.
Vulnerability class: Command Injection (OS Command Injection)
EPSS: 0.002 (7.6th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.5 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L.
Affected products
- Python Pillow
- Python-pillow Pillow — versions < 12.3.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_MISC, Release Notes)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-55798?
- CVE-2026-55798 is a medium-severity vulnerability in Python Pillow, classified under OS Command Injection. CVSS score: 4.5/10. Published 2026-07-06.
- How severe is CVE-2026-55798?
- Medium severity. CVSS v3 base score is 4.5 out of 10.