Vulnerability · Published Apr 13, 2026 · Assigned by PSF

CVE-2026-4786Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()

High 7.1

In plain English

A high-severity command injection in CPython from Python Software Foundation. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.1High
Exploit odds (30 days)0.3%top 78.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8platform-python3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:8platform-python-debug3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:8platform-python-devel3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:10python-unversioned-command3.12.12-3.el10_1.3ALSA-2026:10711
AlmaLinux:10python-unversioned-command3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:9python-unversioned-command3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python-unversioned-command3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python33.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:9python33.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python33.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python3-debug3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:9python3-debug3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:9python3-debug3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:10python3-devel3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:9python3-devel3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python3-devel3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python3-idle3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:8python3-idle3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:9python3-idle3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python3-idle3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python3-libs3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:8python3-libs3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:9python3-libs3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python3-libs3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python3-test3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:8python3-test3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:9python3-test3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:9python3-test3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:10python3-tkinter3.12.13-2.el10_2ALSA-2026:19064
AlmaLinux:8python3-tkinter3.6.8-76.el8_10.alma.1ALSA-2026:11077
AlmaLinux:9python3-tkinter3.9.25-7.el9_8ALSA-2026:19216
AlmaLinux:9python3-tkinter3.9.25-3.el9_7.3ALSA-2026:10949
AlmaLinux:8python3.113.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.113.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:9python3.113.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:8python3.11-debug3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-debug3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:9python3.11-debug3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:8python3.11-devel3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-devel3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:9python3.11-devel3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:8python3.11-idle3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-idle3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:9python3.11-idle3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:8python3.11-libs3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-libs3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:9python3.11-libs3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:8python3.11-rpm-macros3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:8python3.11-test3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-test3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:9python3.11-test3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:8python3.11-tkinter3.11.13-7.el8_10ALSA-2026:11062
AlmaLinux:9python3.11-tkinter3.11.13-9.el9_8ALSA-2026:19175
AlmaLinux:9python3.11-tkinter3.11.13-5.3.el9_7ALSA-2026:10774
AlmaLinux:8python3.123.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.123.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:9python3.123.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-debug3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-debug3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:9python3.12-debug3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:8python3.12-devel3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-devel3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:9python3.12-devel3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:8python3.12-idle3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-idle3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:9python3.12-idle3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:8python3.12-libs3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-libs3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:9python3.12-libs3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:8python3.12-rpm-macros3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:8python3.12-test3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-test3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:9python3.12-test3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:8python3.12-tkinter3.12.13-2.el8_10ALSA-2026:10950
AlmaLinux:9python3.12-tkinter3.12.12-4.el9_7.3ALSA-2026:10745
AlmaLinux:9python3.12-tkinter3.12.13-2.el9_8ALSA-2026:19177
AlmaLinux:10python3.143.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.143.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.143.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.143.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-debug3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-debug3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-debug3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-debug3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-devel3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:10python3.14-devel3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-devel3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:9python3.14-devel3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:10python3.14-freethreading3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-freethreading3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-freethreading3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-freethreading3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-debug3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-freethreading-debug3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-freethreading-debug3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:9python3.14-freethreading-debug3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:10python3.14-freethreading-devel3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-freethreading-devel3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-freethreading-devel3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-freethreading-devel3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-idle3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:10python3.14-freethreading-idle3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-idle3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-freethreading-idle3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-libs3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:10python3.14-freethreading-libs3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-freethreading-libs3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-freethreading-libs3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-test3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-freethreading-test3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-freethreading-test3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-freethreading-test3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-freethreading-tkinter3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-freethreading-tkinter3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-freethreading-tkinter3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:9python3.14-freethreading-tkinter3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:10python3.14-idle3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:10python3.14-idle3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-idle3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-idle3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-libs3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-libs3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-libs3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:9python3.14-libs3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:10python3.14-test3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:10python3.14-test3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:9python3.14-test3.14.5-1.el9_8ALSA-2026:28247
AlmaLinux:9python3.14-test3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:10python3.14-tkinter3.14.4-2.el10_2ALSA-2026:19019
AlmaLinux:10python3.14-tkinter3.14.5-1.el10_2ALSA-2026:28581
AlmaLinux:9python3.14-tkinter3.14.4-2.el9_8ALSA-2026:19176
AlmaLinux:9python3.14-tkinter3.14.5-1.el9_8ALSA-2026:28247
Alpine:v3.21python33.12.14-r0ALPINE-CVE-2026-4786
Alpine:v3.22python33.12.14-r0ALPINE-CVE-2026-4786
Alpine:v3.23python33.12.14-r0ALPINE-CVE-2026-4786
Debian:14pypy37.3.22+dfsg-1DEBIAN-CVE-2026-4786
Debian:14python3.143.14.5-1DEBIAN-CVE-2026-4786
Rocky Linux:8python30:3.6.8-76.el8_10.rocky.0RLSA-2026:11077
Rocky Linux:8python3.110:3.11.13-7.el8_10RLSA-2026:11062
Rocky Linux:9python3.110:3.11.13-5.3.el9_7RLSA-2026:10774
Rocky Linux:9python3.110:3.11.13-9.el9_8RLSA-2026:19175
Rocky Linux:10python3.120:3.12.13-2.el10_2RLSA-2026:19064
Rocky Linux:8python3.120:3.12.13-2.el8_10RLSA-2026:10950
Rocky Linux:9python3.120:3.12.12-4.el9_7.3RLSA-2026:10745
Rocky Linux:9python3.120:3.12.13-2.el9_8RLSA-2026:19177
Rocky Linux:10python3.140:3.14.5-1.el10_2RLSA-2026:28581
Rocky Linux:10python3.140:3.14.4-2.el10_2RLSA-2026:19019
Rocky Linux:9python3.140:3.14.5-1.el9_8RLSA-2026:28247
Rocky Linux:9python3.140:3.14.4-2.el9_8RLSA-2026:19176
Rocky Linux:9python3.90:3.9.25-7.el9_8RLSA-2026:19216
Rocky Linux:9python3.90:3.9.25-3.el9_7.3RLSA-2026:10949
Ubuntu:22.04:LTSjythonno fix listedUBUNTU-CVE-2026-4786
Ubuntu:24.04:LTSjythonno fix listedUBUNTU-CVE-2026-4786
Ubuntu:25.10jythonno fix listedUBUNTU-CVE-2026-4786
Ubuntu:26.04:LTSjythonno fix listedUBUNTU-CVE-2026-4786
Ubuntu:26.10jythonno fix listedUBUNTU-CVE-2026-4786
Ubuntu:22.04:LTSpypy3no fix listedUBUNTU-CVE-2026-4786
Ubuntu:24.04:LTSpypy3no fix listedUBUNTU-CVE-2026-4786
Ubuntu:25.10pypy3no fix listedUBUNTU-CVE-2026-4786
Ubuntu:26.04:LTSpypy3no fix listedUBUNTU-CVE-2026-4786
Ubuntu:26.10pypy3no fix listedUBUNTU-CVE-2026-4786
Ubuntu:22.04:LTSpython3.103.10.12-1~22.04.16UBUNTU-CVE-2026-4786
Ubuntu:22.04:LTSpython3.103.10.12-1~22.04.16USN-8509-1
Ubuntu:24.04:LTSpython3.123.12.3-1ubuntu0.15USN-8509-1
Ubuntu:24.04:LTSpython3.123.12.3-1ubuntu0.15UBUNTU-CVE-2026-4786
Ubuntu:25.10python3.13no fix listedUBUNTU-CVE-2026-4786
Ubuntu:25.10python3.14no fix listedUBUNTU-CVE-2026-4786
Ubuntu:26.04:LTSpython3.143.14.4-1ubuntu0.1UBUNTU-CVE-2026-4786
Ubuntu:26.04:LTSpython3.143.14.4-1ubuntu0.1USN-8509-1

Affected products (as reported)

VendorProductVersions
Python Software Foundation CPython 0 – before 3.10.213.11.0 – before 3.11.163.12.0 – before 3.12.143.13.0 – before 3.13.143.14.0a1 – before 3.14.5rc13.15.0a1 – before 3.15.0b1

Weakness: CWE-77, CWE-88 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L

References