VDB
CVE-2026-28356
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 0.86% · 75.4th percentile
Risk Scores
CVSS 3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS Score
0.86%
75.4th percentile
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| PyPI | multipart | 0, 1.3.0, 0 |
| defnull | multipart | >= 1.3.0, < 1.3.1, < 1.2.2, >= 1.3.0, < 1.3.1 |
Exploit Intelligence
- CIRCL seen: CVE-2026-28356 (circl-sighting)
- CIRCL seen: CVE-2026-28356 (circl-sighting)
- CIRCL seen: CVE-2026-28356 (circl-sighting)
- https://github.com/defnull/multipart/security/advisories/GHSA-p2m9-wcp5-6qw3 (circl)
Timeline
- Mar 12, 2026 CVE Published
- Mar 12, 2026 PoC Published
- Mar 12, 2026 PoC Published
- Mar 13, 2026 EPSS Score
- Mar 13, 2026 PoC Published
- Mar 14, 2026 EPSS Score
- Mar 15, 2026 EPSS Score
- Mar 16, 2026 EPSS Score
- Mar 17, 2026 EPSS Score
- Mar 17, 2026 Coalition ESS Score
- Mar 18, 2026 EPSS Score
- Mar 19, 2026 EPSS Score