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CVE-2026-28356 PUBLISHED CVSS 7.5 HIGH

multipart is a fast multipart/form-data parser for python. Prior to 1.2.2, 1.3.1 and 1.4.0-dev, the parse_options_header() function in multipart.py uses a regular expression with an ambiguous alternation, which can cause exponential backtracking (ReDoS) when parsing maliciously crafted HTTP or multipart segment headers. This can be abused for denial of service (DoS) attacks against web applications using this library to parse request headers or multipart/form-data streams. The issue is fixed in 1.2.2, 1.3.1 and 1.4.0-dev.

EPSS 0.71% · 72.2th percentile

Risk Scores

CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score
0.71%
72.2th percentile

Affected Products

VendorProductVersions
PyPImultipart0, 1.3.0, 0
defnullmultipart>= 1.3.0, < 1.3.1, < 1.2.2, >= 1.3.0, < 1.3.1

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References

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