CVE-2026-28356
multipart - security update
7.5
HIGH
CVSS 3.1
EPSS 0.86%
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.
How to fix CVE-2026-28356
To remediate CVE-2026-28356, upgrade the affected package to a fixed version below.
- —upgrade to 1.2.1-2+deb13u1 or later
- —upgrade to 1.2.1-2+deb13u1 or later
- —upgrade to 1.3.1 or later
Is CVE-2026-28356 being exploited?
Low — EPSS is 0.9%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.2.1-2+deb13u1
- from 0, < 1.2.1-2+deb13u1
- >= 1.3.0, < 1.3.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |