CVE-2026-40347

low-risk
Published 2026-04-18

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.

Do I need to act?

-
0.02% chance of exploitation
EPSS score — low exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10 Medium
NETWORK / LOW complexity

Affected Products (1)

Python-Multipart

Affected Vendors

Fastapiexpert

References (2)

Product https://github.com/Kludex/python-multipart/releases/tag/0.0.26
Vendor Advisory https://github.com/Kludex/python-multipart/security/advisories/GHSA-mj87-hwqh-73...
26
/ 100
low-risk
Severity 21/34 · High
Exploitability 0/34 · Minimal
Exposure 5/34 · Minimal