CVE-2026-4519 — webbrowser.open() allows leading dashes in URLs

Description (CNA)

The webbrowser.open() API would accept leading dashes in the URL which could be handled as command line options for certain web browsers. New behavior rejects leading dashes. Users are recommended to sanitize URLs prior to passing to webbrowser.open().

Affected (CNA)

Vendor / product	Versions
Python Software Foundation / CPython	affected 0 before 3.10.21; affected 3.11.0 before 3.11.16; affected 3.12.0 before 3.12.14; affected 3.13.0 before 3.13.13; affected 3.14.0 before 3.14.4; affected 3.15.0a1 before 3.15.0a8

CWE

No CWE identifiers supplied.

References

ADP enrichment

CVE

No English description supplied.

http://www.openwall.com/lists/oss-security/2026/03/20/1

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

A flaw was found in Python. The `webbrowser.open()` API, used to launch web browsers, does not properly sanitize input. This allows a remote attacker to craft a malicious URL containing leading dashes. When such a URL is opened, certain web browsers may interpret these dashes as command-line options, which could lead to unexpected behavior, information disclosure, or potentially arbitrary code execution, impacting the integrity of the system.