Input validation error in aiohttp - #VU133994
Published: June 9, 2026
Vulnerability identifier: #VU133994
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-20
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 input validation in the C HTTP parser when processing fragmented HTTP request lines. A remote attacker can send specially crafted oversized fragmented lines to cause a denial of service.
Only deployments using the optimized C parser are affected.
Remediation
Install security update from vendor's website.