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CVE-2026-40347

Python-Multipart affected by Denial of Service via large multipart preamble or epilogue data

Published: Apr 17, 2026Updated: Apr 18, 2026 Sources: CVE List NVD
NVD MITRE
5.3CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:L
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:LAvailability
Low

Weaknesses

CWE-400CWE-834

Affected Products

python-multipart
Kludex

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Impact
View detailed technique mapping

References

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

Timeline

Published
Apr 17, 2026
Last Updated
Apr 18, 2026

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