Python-Multipart: Negative Content-Length in parse_form buffers the entire body in memory

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Summary

CVECVE-2026-53540
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-22 18:16:44 UTC
Updated2026-06-23 15:56:11 UTC
DescriptionPython-Multipart is a streaming multipart parser for Python. Prior to 0.0.31, parse_form() did not validate the Content-Length header before using it to bound its chunked read of the request body. A negative Content-Length turned the bounded read into a read-until-EOF, so the entire body was loaded into memory in a single read instead of in fixed-size chunks. This vulnerability is fixed in 0.0.31.

Risk And Classification

Primary CVSS: v3.1 3.7 LOW from [email protected]

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.002170000 probability, percentile 0.120770000 (date 2026-06-25)

Problem Types: CWE-1284 | CWE-1284 CWE-1284: Improper Validation of Specified Quantity in Input

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED3.7LOWCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Kludex Python-multipart affected < 0.0.31 Not specified

References

ReferenceSourceLinkTags
github.com/Kludex/python-multipart/security/advisories/GHSA-v9pg-7xvm-68hf [email protected] github.com
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