CVE-2026-40347
python-multipart affected by Denial of Service via large multipart preamble or epilogue data
5.3
MEDIUM
CVSS 3.1
EPSS 0.02%
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.
How to fix CVE-2026-40347
To remediate CVE-2026-40347, upgrade the affected package to a fixed version below.
- —no fix listed
- —upgrade to 0.0.26 or later
Is CVE-2026-40347 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (2)
- from 0
- from 0, < 0.0.26
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | MEDIUM5.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |