CVE-2026-54283: CWE-770: Allocation of Resources Without Limits or Throttling in Kludex starlette
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.
AI Analysis
Technical Summary
Starlette, a lightweight ASGI framework, enforces limits on multipart/form-data requests via max_fields and max_part_size parameters to control resource consumption. However, from versions 0.4.1 up to but not including 1.3.1, these limits are silently ignored for application/x-www-form-urlencoded content types. This allows an unauthenticated attacker to send urlencoded requests with unlimited fields or field sizes, potentially causing resource exhaustion. The vulnerability is identified as CWE-770 (Allocation of Resources Without Limits or Throttling) and is fixed in version 1.3.1.
Potential Impact
An attacker can cause denial of service by sending large or numerous urlencoded form fields that bypass configured limits, leading to resource exhaustion on the server. There is no confidentiality or integrity impact reported. The CVSS score of 7.5 reflects a high severity denial of service vulnerability exploitable remotely without authentication.
Mitigation Recommendations
Upgrade Starlette to version 1.3.1 or later, where this issue is fixed. Patch status is not explicitly stated but the description confirms the fix in 1.3.1. Until then, applications should be aware that configured limits do not apply to application/x-www-form-urlencoded requests and may consider additional application-level validation or filtering.
CVE-2026-54283: CWE-770: Allocation of Resources Without Limits or Throttling in Kludex starlette
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.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Starlette, a lightweight ASGI framework, enforces limits on multipart/form-data requests via max_fields and max_part_size parameters to control resource consumption. However, from versions 0.4.1 up to but not including 1.3.1, these limits are silently ignored for application/x-www-form-urlencoded content types. This allows an unauthenticated attacker to send urlencoded requests with unlimited fields or field sizes, potentially causing resource exhaustion. The vulnerability is identified as CWE-770 (Allocation of Resources Without Limits or Throttling) and is fixed in version 1.3.1.
Potential Impact
An attacker can cause denial of service by sending large or numerous urlencoded form fields that bypass configured limits, leading to resource exhaustion on the server. There is no confidentiality or integrity impact reported. The CVSS score of 7.5 reflects a high severity denial of service vulnerability exploitable remotely without authentication.
Mitigation Recommendations
Upgrade Starlette to version 1.3.1 or later, where this issue is fixed. Patch status is not explicitly stated but the description confirms the fix in 1.3.1. Until then, applications should be aware that configured limits do not apply to application/x-www-form-urlencoded requests and may consider additional application-level validation or filtering.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-12T17:46:37.292Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a39735ceed863c81e39629e
Added to database: 06/22/2026, 17:39:40 UTC
Last enriched: 06/29/2026, 21:51:49 UTC
Last updated: 08/06/2026, 00:41:14 UTC
Views: 87
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