CVE Database›CVE-2026-4786

CVE-2026-4786

python: cpython: Python: Arbitrary code execution via command injection in webbrowser.open() API

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Severity

Important

Red Hat Product Security

7.1

CVSS 3.1

Review impact separately from score.

Published · April 14, 2026

Updated · October 16, 2026

Description

A flaw was found in the Python webbrowser.open() API. If a specially crafted URL containing "%action" is processed, an attacker could bypass a previous mitigation for CVE-2026-4519. This bypass allows for command injection into the underlying shell, potentially leading to arbitrary code execution.

Statement

This flaw in the Python webbrowser.open() API allows for command injection and arbitrary code execution when processing specially crafted URLs containing "%action". This bypasses a previous mitigation for CVE-2026-4519.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

CVSS / CWE

CVSS 3.1 · 7.1
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L

CWE-88 · Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')