VULNERABILITY INTELLIGENCE

CVE-2026-28356

CVSS score7.5 HIGH
EPSS probability0.76%
CISA KEVNot currently listed
Published2026-03-12
Last modified2026-08-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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.

Weakness classification

  • security-advisories@github.com: CWE-1333
  • 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-1333

Primary references