Python 3.15.0 Alpha 1

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().

Published: 2026-03-20T15:08:32.576Z
Updated: 2026-04-13T21:47:40.137Z

If the value passed to os.path.expandvars() is user-controlled a performance degradation is possible when expanding environment variables.

Published: 2025-10-31T16:41:34.983Z
Updated: 2026-03-03T14:43:01.737Z

When loading a plist file, the plistlib module reads data in size specified by the file itself, meaning a malicious file can cause OOM and DoS issues

Published: 2025-12-01T18:13:32.739Z
Updated: 2026-03-03T14:41:54.597Z

When reading an HTTP response from a server, if no read amount is specified, the default behavior will be to use Content-Length. This allows a malicious server to cause the client to read large amounts of data into memory, potentially causing OOM or other DoS.

Published: 2025-12-01T18:02:38.483Z
Updated: 2026-03-03T14:41:48.702Z

When passing data to the b64decode(), standard_b64decode(), and urlsafe_b64decode() functions in the "base64" module the characters "+/" will always be accepted, regardless of the value of "altchars" parameter, typically used to establish an "alternative base64 alphabet" such as the URL safe alphabet. This behavior matches what is recommended in earlier base64 RFCs, but newer RFCs now recommend either dropping characters outside the specified base64 alphabet or raising an error. The old behavior has the possibility of causing data integrity issues. This behavior can only be insecure if your application uses an alternate base64 alphabet (without "+/"). If your application does not use the "altchars" parameter or the urlsafe_b64decode() function, then your application does not use an alternative base64 alphabet. The attached patches DOES NOT make the base64-decode behavior raise an error, as this would be a change in behavior and break existing programs. Instead, the patch deprecates the behavior which will be replaced with the newly recommended behavior in a future version of Python. Users are recommended to mitigate by verifying user-controlled inputs match the base64 alphabet they are expecting or verify that their application would not be affected if the b64decode() functions accepted "+" or "/" outside of altchars.

Published: 2026-01-21T19:34:47.979Z
Updated: 2026-01-22T20:12:56.421Z

When building nested elements using xml.dom.minidom methods such as appendChild() that have a dependency on _clear_id_cache() the algorithm is quadratic. Availability can be impacted when building excessively nested documents.

Published: 2025-12-03T18:55:32.222Z
Updated: 2026-03-03T14:41:38.821Z