CVE-2026-34517
AIOHTTP: Late size enforcement for non-file multipart fields causes memory DoS
Description
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.
INFO
Published Date :
April 1, 2026, 9:16 p.m.
Last Modified :
April 15, 2026, 1:54 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | LOW | [email protected] |
Solution
- Update aiohttp to version 3.13.4 or later.
- Monitor memory usage after the update.
- Review multipart form handling logic.
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-2026-34517.
| URL | Resource |
|---|---|
| https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145 | Patch |
| https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 | Release Notes |
| https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j | Patch 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-2026-34517 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-2026-34517
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).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-34517 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-34517 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]
Apr. 15, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Added CPE Configuration OR *cpe:2.3:a:aiohttp:aiohttp:*:*:*:*:*:*:*:* versions up to (excluding) 3.13.4 Added Reference Type GitHub, Inc.: https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j Types: Patch, Vendor Advisory -
New CVE Received by [email protected]
Apr. 01, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-770 Added Reference https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145 Added Reference https://github.com/aio-libs/aiohttp/releases/tag/v3.13.4 Added Reference https://github.com/aio-libs/aiohttp/security/advisories/GHSA-3wq7-rqq7-wx6j