CVE-2026-54283
Description
A flaw was found in Starlette where the request.form() method silently ignores configured resource limits (max_fields and max_part_size) when parsing application/x-www-form-urlencoded data. An unauthenticated attacker can exploit this by sending a urlencoded request body with an arbitrarily large number of fields or an oversized field, causing denial of service through resource exhaustion.
Statement
A flaw was found in Starlette where the request.form() method silently ignores configured resource limits (max_fields and max_part_size) when parsing application/x-www-form-urlencoded data. An unauthenticated attacker can exploit this by sending a urlencoded request body with an arbitrarily large number of fields or an oversized field, causing denial of service through resource exhaustion. This only affects applications that explicitly call request.form() on urlencoded input; JSON-only APIs and services where Starlette is a transitive dependency not used for form parsing are not affected.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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