CVE-2023-25577

Werkzeug may allow high resource usage when parsing multipart form data with many fields

HIGH
7.5
CVSS Score
Published: February 14, 2023 at 07:56 PM UTC
Updated: June 17, 2026 at 05:41 AM UTC
2 products affected across 2 vendorsWerkzeugWerkzeug

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.2.3
Affected range stops below 2.2.3, so it looks safe — our inference, not a vendor statement
v < 2.2.3
Affected range stops below 2.2.3, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-770

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