CVE-2026-55798
Description
A flaw was found in Pillow, a Python imaging library. The WindowsViewer.get_command() function constructed a command-line interface (CLI) shell command by directly embedding a file path without proper escaping. This allowed shell metacharacters within the file path to inject arbitrary commands into cmd.exe. An attacker could exploit this to execute unauthorized commands on the system.
Statement
A flaw was found in Pillow, a Python imaging library. The WindowsViewer.get_command() method constructs a cmd.exe shell command by directly embedding a file path into an f-string without applying shlex.quote() or equivalent escaping. This string is then passed to subprocess.Popen with shell=True, allowing shell metacharacters in the file path to inject and execute arbitrary cmd.exe commands. The vulnerability is specific to the Windows platform; the Linux (UnixViewer) and macOS (MacViewer) equivalents already apply proper shell quoting.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.5 | N/A | 4.5 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | Low | N/A | Low |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
cve.org: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:L
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability,Non-Repudiation
Technical Impact: Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities
Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.
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