CPython webbrowser.open() Leading-Dash URL Injection in 3.15
CVE-2026-4519 Published on March 20, 2026
webbrowser.open() allows leading dashes in URLs
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().
Weakness Type
Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
Products Associated with CVE-2026-4519
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Affected Versions
Python Software Foundation CPython:- Before 3.13.13 is affected.
- Version 3.14.0 and below 3.14.4 is affected.
- Version 3.15.0a1 and below 3.15.0a8 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.