Medium [CVE-2026-55798] Arbitrary command injection via shell metacharacters in file paths
This medium-severity Red Hat Linux advisory covers CVE-2026-55798.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
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.
An attacker could exploit this to execute unauthorized commands on the system. The vulnerability is specific to the Windows platform; the Linux (UnixViewer) and macOS (MacViewer) equivalents already apply proper shell quoting.
Red Hat severity: Moderate — CVSS 4.5 (CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L). Weakness: CWE-78.
Red Hat lists Exploit Intelligence; Lightspeed Core; OpenShift Lightspeed; Red Hat AI Inference Server; Red Hat Ansible Automation Platform 2; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux AI (RHEL AI) 3; Red Hat OpenShift AI (RHOAI); Red Hat Quay 3; Red Hat Satellite 6 as not affected.
Is CVE-2026-55798 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-55798 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-55798?
Upgrade to a fixed release named by Red Hat:
- 12.3.0
Confirm against the vendor advisory before you patch.
- < 12.3.0
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
Mitigation checklist
- This vulnerability is specific to the WindowsViewer class in Pillow, which is only invoked on Windows systems. Red Hat products ship and run on Linux, where the UnixViewer class is used instead, which properly applies shlex.quote() to file paths. The vulnerable Windows code path is not reachable on Red Hat's supported platforms. Users can upgrade to Pillow 12.3.0 or later, which adds proper escaping to the Windows code path.
Official advisory · high-confidence parse· fetched 11 days ago·verify at source
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