aio-libs aiohttp up to 3.13.3 Multipart Form client_max_size allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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5.1$0-$5k0.00

Summaryinfo

A vulnerability categorized as problematic has been discovered in aio-libs aiohttp up to 3.13.3. This affects the function client_max_size of the component Multipart Form Handler. Executing a manipulation can lead to allocation of resources. This vulnerability is handled as CVE-2026-34517. The attack can be executed remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in aio-libs aiohttp up to 3.13.3. It has been declared as problematic. This vulnerability affects the function client_max_size of the component Multipart Form Handler. The manipulation with an unknown input leads to a allocation of resources vulnerability. The CWE definition for the vulnerability is CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. As an impact it is known to affect availability. CVE summarizes:

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, for some multipart form fields, aiohttp read the entire field into memory before checking client_max_size. This issue has been patched in version 3.13.4.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-34517 since 03/30/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 3.13.4 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch cbb774f38330563422ca0c413a71021d7b944145 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at CNNVD (CNNVD-202604-216). Once again VulDB remains the best source for vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.1

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: aiohttp 3.13.4
Patch: cbb774f38330563422ca0c413a71021d7b944145

Timelineinfo

03/30/2026 CVE reserved
04/02/2026 +3 days Advisory disclosed
04/02/2026 +0 days VulDB entry created
04/02/2026 +0 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-3wq7-rqq7-wx6j
Status: Confirmed

CVE: CVE-2026-34517 (🔒)
GCVE (CVE): GCVE-0-2026-34517
GCVE (VulDB): GCVE-100-354796
CNNVD: CNNVD-202604-216 - aiohttp 安全漏洞

Entryinfo

Created: 04/02/2026 02:40
Updated: 04/02/2026 22:37
Changes: 04/02/2026 02:40 (72), 04/02/2026 22:37 (6)
Complete: 🔍
Cache ID: 216:AF4:103

Once again VulDB remains the best source for vulnerability data.

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