---
id: CVE-2023-25577
aliases:
  - GHSA-xg9f-g7g7-2323
  - PYSEC-2023-58
title: High resource usage when parsing multipart form data with many fields
summary: High resource usage when parsing multipart form data with many fields
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
vendor: werkzeug
product: werkzeug
ecosystem: pip
affected:
  - werkzeug < 2.2.3
patched:
  - werkzeug 2.2.3
published: '2023-02-15'
updated: '2026-09-10'
sourceUpdated: '2026-09-10T03:49:52.206975143Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-xg9f-g7g7-2323'
references:
  - url: >-
      https://github.com/pallets/werkzeug/security/advisories/GHSA-xg9f-g7g7-2323
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2023-25577'
  - url: >-
      https://github.com/pallets/werkzeug/commit/517cac5a804e8c4dc4ed038bb20dacd038e7a9f1
  - url: 'https://github.com/pallets/werkzeug'
  - url: 'https://github.com/pallets/werkzeug/releases/tag/2.2.3'
  - url: >-
      https://github.com/pypa/advisory-database/tree/main/vulns/werkzeug/PYSEC-2023-58.yaml
  - url: 'https://security.netapp.com/advisory/ntap-20230818-0003'
  - url: 'https://www.debian.org/security/2023/dsa-5470'
tags:
  - osv
  - pip
epss: 0.0142
epssPercentile: 0.71702
ingestedAt: '2026-09-12T03:13:01.739Z'
---

## Overview

Werkzeug's multipart form data parser will parse an unlimited number of parts, including file parts. Parts can be a small amount of bytes, but each requires CPU time to parse and may use more memory as Python data. If a request can be made to an endpoint that accesses `request.data`, `request.form`, `request.files`, or `request.get_data(parse_form_data=False)`, it can cause unexpectedly high resource usage.

This allows an attacker to cause a denial of service by sending crafted multipart data to an endpoint that will parse it. The amount of CPU time required can block worker processes from handling legitimate requests. The amount of RAM required can trigger an out of memory kill of the process. Unlimited file parts can use up memory and file handles. If many concurrent requests are sent continuously, this can exhaust or kill all available workers.

## Affected packages

- `werkzeug < 2.2.3`

## Remediation

Upgrade to a patched release:

- `werkzeug 2.2.3`