CVE-2026-54283
Starlette: request.form() limits silently ignored for application/x-www-form-urlencoded enable DoS
Description
Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1.
INFO
Published Date :
June 22, 2026, 6:16 p.m.
Last Modified :
June 26, 2026, 7:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update Starlette to version 1.3.1.
- Verify application configuration for form data limits.
Public PoC/Exploit Available at Github
CVE-2026-54283 has a 10 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-54283.
| URL | Resource |
|---|---|
| https://github.com/Kludex/starlette/security/advisories/GHSA-82w8-qh3p-5jfq | Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54283 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-54283
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
A security-first CLI tool that scans codebases for hardcoded secrets and tracks remediation through a local SQLite database. Self-gating CI/CD pipeline with Trivy container scanning and Semgrep SAST. Built as a DevSecOps portfolio project demonstrating secure development practices and vulnerability management.
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Python Dockerfile
None
None
Dockerfile Python HTML
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Dockerfile Makefile Python Shell
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Repositorio Obligatorio Devops Marzo 2026 - Nicolas Recoba - Facundo Pelufo - Emiliano Olivera
Dockerfile HTML TypeScript Python Go HCL JavaScript
a lightweight Platform-as-a-Service (PaaS) that allows developers to deploy applications by simply pushing their code. It automatically builds, deploys, and exposes applications via a public URL.
Makefile Shell Dockerfile Python Mako HTML JavaScript TypeScript CSS YARA
None
PowerShell Batchfile Python CSS HTML Shell JavaScript C++ C# Dart
NotebookLM MCP CLI - Access NotebookLM via Claude with security fixes and FastMCP 1.0 compatibility
Python
All Public RunWhen Helm Charts - Managed by terraform
Shell Dockerfile Go Template
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-54283 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-54283 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jun. 26, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:* versions from (including) 0.4.1 up to (excluding) 1.3.1 Added Reference Type GitHub, Inc.: https://github.com/Kludex/starlette/security/advisories/GHSA-82w8-qh3p-5jfq Types: Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 23, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-54283', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-23T16:06:30.546768Z'} -
New CVE Received by [email protected]
Jun. 22, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Kludex', 'product': 'starlette', 'versions': [{'status': 'affected', 'version': '>= 0.4.1, < 1.3.1'}]}] Added Description Starlette is a lightweight ASGI framework/toolkit. From 0.4.1 until 1.3.1, request.form() accepts max_fields and max_part_size to bound resource consumption while parsing form data. These limits are enforced for multipart/form-data, but silently ignored for application/x-www-form-urlencoded. An unauthenticated attacker can therefore send a urlencoded body with an arbitrarily large number of fields or an arbitrarily large field, even when the application configured limits it believed would apply. This vulnerability is fixed in 1.3.1. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-770 Added Reference https://github.com/Kludex/starlette/security/advisories/GHSA-82w8-qh3p-5jfq