HTTP Request Smuggling Affecting python-multipart package, versions [,0.0.30)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-PYTHONMULTIPART-17344732
- published16 Jun 2026
- disclosed15 Jun 2026
- creditmaxisbey
Introduced: 15 Jun 2026
NewCVE-2026-53538 (opens in a new tab)How to fix?
Upgrade python-multipart to version 0.0.30 or higher.
Overview
python-multipart is an A streaming multipart parser for Python
Affected versions of this package are vulnerable to HTTP Request Smuggling through the QuerystringParser function. An attacker can bypass upstream validation and inject or override form fields by crafting specially formatted application/x-www-form-urlencoded bodies that exploit differences in field separator parsing.
Note:
This is only exploitable if there is an upstream body-inspecting component (a WAF, API gateway, proxy, etc.) between the attacker and the application, and that intermediary follows the WHATWG standard (treating only & as a separator, not ;).