PythonMultipart <0.0.27: DoS via unlimited multipartpart headers
CVE-2026-42561 Published on May 13, 2026

Python-Multipart: Denial of Service via unbounded multipart part headers
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.

NVD

Vulnerability Analysis

CVE-2026-42561 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
NONE
Integrity Impact:
NONE
Availability Impact:
HIGH

Weakness Types

Allocation of Resources Without Limits or Throttling

The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

Unchecked Input for Loop Condition

The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.


Products Associated with CVE-2026-42561

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Red Hat Exploit Intelligence
 
Red Hat Migration Toolkit Applications
 
Red Hat Openshift Lightspeed
 
Red Hat Ai Inference Server
 
Red Hat Ansible Automation Platform
 
Red Hat Enterprise Linux Ai
 
Red Hat Openshift Ai
 
Red Hat Satellite
 

Affected Versions

Kludex python-multipart: Red Hat Exploit Intelligence: Red Hat Migration Toolkit for Applications 8: Red Hat OpenShift Lightspeed: Red Hat AI Inference Server: Red Hat Ansible Automation Platform 2: Red Hat Enterprise Linux AI (RHEL AI) 3: Red Hat OpenShift AI (RHOAI): Red Hat Satellite 6:

Exploit Probability

EPSS
0.33%
Percentile
24.71%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.