IA Squad
SearchPT
python · python-multipartHeads-up

python-multipart: QuerystringParser no longer treats ';' as separator

QuerystringParser no longer treats ';' as a field separator in application/x-www-form-urlencoded bodies; only '&' is used, aligning with the WHATWG URL standard

16 Jun 2026Read 1 minSeverity: schedule it

What changed

QuerystringParser no longer treats ';' as a field separator in application/x-www-form-urlencoded bodies; only '&' is used, aligning with the WHATWG URL standard.

Who it affects

Applications using python-multipart for parsing url-encoded form data, especially those behind a WAF or gateway that follows WHATWG rules, and users of Starlette/FastAPI request.form().

What to do today

Upgrade python-multipart to version 0.0.30 or later.

The trail
Collected Audited Written Published