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CVE-2026-42561

33
FAUCET Score

Python-Multipart is a streaming multipart parser for Python. Prior to 0.0.27, python-multipart has a denial of service vulnerability in multipart part header parsing. When parsing multipart/form-data, MultipartParser previously had no limit on the number of part headers or the size of an individual part header. An attacker could send a request with either many repeated headers without terminating the header block or a single very large header value, causing excessive CPU work before request rejection or completion. This vulnerability is fixed in 0.0.27.

First published: May 13, 2026Last modified: May 13, 2026

Impacted Technologies

VendorProductVersion(s)CPE
KludexPython-Multipart
< 0.0.27CNA affected

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.72%
Probability of exploitation in next 30 days
EPSS Percentile
50.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0072 is in the 26th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

pippatch availablevia ghsa
Product: python-multipartFixed in: 0.0.27

Vendor Advisories (1)

pipGHSA-pp6c-gr5w-3c5ghigh

python-multipart has Denial of Service via unbounded multipart part headers

May 6, 2026

References

access.redhat.com / errata/RHSA-2026:37275
access.redhat.com / errata/RHSA-2026:42132
access.redhat.com / errata/RHSA-2026:42142
access.redhat.com / errata/RHSA-2026:43038
access.redhat.com / errata/RHSA-2026:44696
access.redhat.com / security/cve/CVE-2026-42561
bugzilla.redhat.com / show_bug.cgi
security.access.redhat.com / data/csaf/v2/vex/2026/cve-2026-42561.json
github.com / Kludex/python-multipart/security/advisories/GHSA-pp6c-gr5w-3c5g