// For flags

CVE-2026-4786

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

Severity Score

7.0
*CVSS v4

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track*
*SSVC
Descriptions

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.

*Credits: an7y, Seth Larson, Stan Ulbrych
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Active
System
Vulnerable | Subsequent
Confidentiality
High
None
Integrity
High
None
Availability
None
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Track*
Exploitation
None
Automatable
No
Tech. Impact
Total
* Organization's Worst-case Scenario
Timeline
  • 2026-03-24 CVE Reserved
  • 2026-04-13 CVE Published
  • 2026-04-29 CVE Updated
  • 2026-05-15 EPSS Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-77: Improper Neutralization of Special Elements used in a Command ('Command Injection')
CAPEC
Affected Vendors, Products, and Versions
Vendor Product Version Other Status
Vendor Product Version Other Status <-- --> Vendor Product Version Other Status
Python Software Foundation
Search vendor "Python Software Foundation"
 CPython
Search vendor "Python Software Foundation" for product "CPython"
 < 3.15.0
Search vendor "Python Software Foundation" for product "CPython" and version " < 3.15.0"
en
Affected