High severity · published Apr 13, 2026
CVE-2026-4786
Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()
7.1
CVSS
0.3%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L
Attack vector
Network
Complexity
High
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
Low
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CP
CPython · Python Software Foundation
before 3.10.21; 3.11.0 before 3.11.16; 3.12.0 before 3.12.14; 3.13.0 before 3.13.14; 3.14.0a1 before 3.14.5rc1; 3.15.0a1 before 3.15.0b1 · source: vendor
RB
RHEL-8 based Middleware Containers · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat AI Inference Server 3.2 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat AI Inference Server 3.3 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 10.0 Extended Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSION · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 7 Extended Lifecycle Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8 · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On · Red Hat
All versions, or not specified · source: CISA
RH
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support · Red Hat
All versions, or not specified · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-4786
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-4786
github.com
https://github.com/python/cpython/commit/28b4ad38067bbdad34edfcd03ad2de5f06387e53
github.com
https://github.com/python/cpython/commit/a4d3edf3a6ecfde504d02126410d2a65a859b744
github.com
https://github.com/python/cpython/commit/c5767a72838a8dda9d6dc5d3558075b055c56bca
github.com
https://github.com/python/cpython/commit/d22922c8a7958353689dc4763dd72da2dea03fff
github.com
https://github.com/python/cpython/commit/d6d68494be70bdbda20f89f83801ba52ec37daa4
github.com
https://github.com/python/cpython/commit/f4654824ae0850ac87227fb270f9057477946769
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