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)
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (6.8th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Python Pillow
- Python-Pillow Pillow — versions < 12.3.0
Weakness classification (CWE)
References
- github.com/python-pillow/Pillow/blob/main/docs/releasenotes/12.3.0.rst (Release Notes)
- github.com/python-pillow/Pillow/commit/8404ea5fe5df40fc34aa1e51403dd6fce0778b8a (Patch)
- github.com/python-pillow/Pillow/commit/88194166691b7b603529b8b036ab3ab9cedd2de4 (Patch)
- github.com/python-pillow/Pillow/commit/b0e06caa64c1405aa3da0bb1d2bd9a77ca22de7f (Patch)
- github.com/python-pillow/Pillow/security/advisories/GHSA-4x4j-2g7c-83w6 (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.