CVE-2026-4519 PUBLISHED

webbrowser.open() allows leading dashes in URLs

Assigner: PSF
Reserved: 20.03.2026 Published: 20.03.2026 Updated: 20.03.2026

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().

Metrics

CVSS 4.0

CVSS Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS Score: 5.7

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

Product Status

Vendor	Python Software Foundation
Product	CPython
Versions	Default: unaffected affected from 0 to 3.15.0 (excl.)

Credits

Seth Larson coordinator
Gregory P. Smith remediation reviewer

CVE-2026-4519 PUBLISHED

webbrowser.open() allows leading dashes in URLs

Metrics

Product Status

Credits

References