Excessive Iteration Affecting python-multipart package, versions [,0.0.26)


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

Exploit Maturity
Proof of Concept

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  • Snyk IDSNYK-PYTHON-PYTHONMULTIPART-16078395
  • published16 Apr 2026
  • disclosed15 Apr 2026
  • creditHamdaanAliQuatil

Introduced: 15 Apr 2026

NewCVE-2026-40347  (opens in a new tab)
CWE-834  (opens in a new tab)

How to fix?

Upgrade python-multipart to version 0.0.26 or higher.

Overview

python-multipart is an A streaming multipart parser for Python

Affected versions of this package are vulnerable to Excessive Iteration in the parsing performed by multipart.py. An attacker can degrade performance by sending multipart requests with very large preamble or epilogue sections, causing excessive CPU consumption. The patterns of input that trigger inefficient processing are large numbers of CR or LF bytes before the first boundary, and large amounts of data after the closing boundary.

Details

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

  • High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

  • Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

CVSS Base Scores

version 4.0
version 3.1