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.
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History
Thu, 12 Mar 2026 17:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | ReDoS in multipart 1.3.0 - `parse_options_header()` | |
| Weaknesses | CWE-1333 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-03-12T16:45:01.070Z
Reserved: 2026-02-26T18:38:13.890Z
Link: CVE-2026-28356
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Status : Awaiting Analysis
Published: 2026-03-12T17:16:50.080
Modified: 2026-03-12T21:07:53.427
Link: CVE-2026-28356
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OpenCVE Enrichment
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