CVSS 4.0
1.7 lowCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:UCVE-2025-53643
Low (1.7) in aiohttp aiohttp. EPSS 0.4% chance of exploitation in the next 30 days. Fixed in aiohttp 3.12.14.
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.12.14, the Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request. If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. Version 3.12.14 contains a patch for this issue.
Severity
CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N- EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-31)
- CWE
- CWE-444
- Published
- Modified
- Record from
- the NVD, synced
Affected
- aiohttp:aiohttp
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-9548-qrrj-x5pj | PyPI | aiohttp | <3.12.14 | 3.12.14 |
| PYSEC-2026-1104 | PyPI | aiohttp | <3.12.14 | 3.12.14 |