Denial of Service Vulnerability in AIOHTTP Framework by Aio-libs
CVE-2026-128126

8.7HIGH

Key Information:

Vendor

Aio-libs

Status
Aiohttp
Vendor
CVE Published:
13 November 2026

What is CVE-2026-128126?

AIOHTTP, a popular asynchronous HTTP client/server framework for Python, is susceptible to a denial of service vulnerability. Prior to version 3.14.4, the Request.post() method does not impose limits on the number of fields in a URL-encoded form body. This oversight allows a remote attacker to craft a massive form POST request containing numerous repeated keys. When processed, this can cause significant delays and even block the event loop, effectively crippling the application. A patch has been implemented in version 3.14.4 to mitigate this issue, enhancing the framework's resilience against such attacks.

Affected Version(s)

aiohttp < 3.14.4

References

https://github.com/aio-libs/aiohttp/security/advisories/G...
x_refsource_CONFIRM
https://github.com/aio-libs/aiohttp/pull/13738
x_refsource_MISC
https://github.com/aio-libs/aiohttp/pull/13741
x_refsource_MISC

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.