---
id: CVE-2026-4786
title: "Mitgation of\_CVE-2026-4519 was incomplete"
summary: "Mitgation of\_CVE-2026-4519 was incomplete. If the URL contained \"%action\" the mitigation could be bypassed for certain browser types the \"webbrowser.open()\" API could have commands injected into the underlying shell. See\_CVE-2026-4519 fo…"
severity: high
cvss: 7.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L'
cwe:
  - CWE-77
  - CWE-88
published: '2026-04-13'
updated: '2026-07-06'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-4786'
references:
  - url: >-
      https://github.com/python/cpython/commit/28b4ad38067bbdad34edfcd03ad2de5f06387e53
    label: cna@python.org
  - url: >-
      https://github.com/python/cpython/commit/c5767a72838a8dda9d6dc5d3558075b055c56bca
    label: cna@python.org
  - url: >-
      https://github.com/python/cpython/commit/d22922c8a7958353689dc4763dd72da2dea03fff
    label: cna@python.org
  - url: >-
      https://github.com/python/cpython/commit/d6d68494be70bdbda20f89f83801ba52ec37daa4
    label: cna@python.org
  - url: >-
      https://github.com/python/cpython/commit/f4654824ae0850ac87227fb270f9057477946769
    label: cna@python.org
  - url: 'https://github.com/python/cpython/issues/148169'
    label: cna@python.org
  - url: 'https://github.com/python/cpython/pull/148170'
    label: cna@python.org
  - url: >-
      https://mail.python.org/archives/list/security-announce@python.org/thread/JQDUNJVB4AQNTJECSUKOBDU3XCJIPSE5/
    label: cna@python.org
  - url: 'https://access.redhat.com/errata/RHSA-2026:10117'
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
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    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-4786'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2458049'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4786.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.0029
epssPercentile: 0.21827
ingestedAt: '2026-07-06T17:44:51.141Z'
---

## Overview

Mitgation of CVE-2026-4519 was incomplete. If the URL contained "%action" the mitigation could be bypassed for certain browser types the "webbrowser.open()" API could have commands injected into the underlying shell. See CVE-2026-4519 for details.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.