CVE-2026-4786
Incomplete mitigation of CVE-2026-4519, %action expansion for command injection to webbrowser.open()
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.
INFO
Published Date :
April 13, 2026, 10:16 p.m.
Last Modified :
April 29, 2026, 4:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update the webbrowser.open() API implementation.
- Sanitize all URL inputs.
- Validate URL parameters strictly.
- Test mitigation thoroughly.
Public PoC/Exploit Available at Github
CVE-2026-4786 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-4786.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-4786 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-4786
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Hardened Docker infrastructure for an LLM based swedish language tutor
Python JavaScript HTML Go Template CSS
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-4786 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-4786 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Apr. 29, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/28b4ad38067bbdad34edfcd03ad2de5f06387e53 Added Reference https://github.com/python/cpython/commit/d6d68494be70bdbda20f89f83801ba52ec37daa4 -
CVE Modified by [email protected]
Apr. 14, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/c5767a72838a8dda9d6dc5d3558075b055c56bca Added Reference https://github.com/python/cpython/commit/d22922c8a7958353689dc4763dd72da2dea03fff Added Reference https://github.com/python/cpython/commit/f4654824ae0850ac87227fb270f9057477946769 -
New CVE Received by [email protected]
Apr. 13, 2026
Action Type Old Value New Value Added 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. Added CVSS V4.0 AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-77 Added Reference https://github.com/python/cpython/issues/148169 Added Reference https://github.com/python/cpython/pull/148170 Added Reference https://mail.python.org/archives/list/[email protected]/thread/JQDUNJVB4AQNTJECSUKOBDU3XCJIPSE5/