Resource exhaustion in aiohttp - CVE-2026-34517
Published: April 26, 2026
Vulnerability identifier: #VU127950
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-34517
CWE-ID: CWE-400
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: aio-libs
Affected software:
aiohttp
aiohttp
Detailed vulnerability description
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to improper resource management in Request.post() when processing specially crafted multipart form fields. A remote attacker can send a specially crafted multipart request to cause a denial of service.
The issue affects non-file multipart fields that are read into memory before the client_max_size check is enforced.
How to mitigate CVE-2026-34517
Install security update from vendor's website.