# CVE-2026-40347

## Summary

- **CVE ID:** CVE-2026-40347
- **Severity:** MEDIUM
- **CVSS Score:** 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
- **CWE:** CWE-400, CWE-834
- **Published:** Apr 17, 2026
- **Last Modified:** Apr 20, 2026

## Description

Python-Multipart is a streaming multipart parser for Python. Versions prior to 0.0.26 have a denial of service vulnerability when parsing crafted `multipart/form-data` requests with large preamble or epilogue sections. Upgrade to version 0.0.26 or later, which skips ahead to the next boundary candidate when processing leading CR/LF data and immediately discards epilogue data after the closing boundary.

## Affected Products

- Kludex — python-multipart (< 0.0.26)

## References

- [CNA](https://github.com/Kludex/python-multipart/security/advisories/GHSA-mj87-hwqh-73pj)
- [CNA](https://github.com/Kludex/python-multipart/releases/tag/0.0.26)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.35%
- **EPSS Percentile:** 28.2

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._