REDHAT-BUG-2510825: High severity aiohttp aiohttp vulnerability

Published Aug 3, 2026
·
Updated

AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.3, an out-of-bounds heap read could occur in the C response parser while building an error message for a malformed response. An attacker controlled server, or possibly an accidental response, could trigger a DoS in the client. The vulnerable path was error message construction in aiohttp/httpparser.pyx, where an llhttp error-position pointer was used to build a snippet for malformed chunked responses and malformed request or response bytes at the buffer end. This issue is fixed in version 3.14.3.

Affected Software

1 affected component
aiohttp aiohttp<3.14.3

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade aiohttp to a version that resolves this vulnerability.

    Fixed in 3.14.3

Event History

Aug 3, 2026
Data Sourced
via Red Hat·10:03 PM
DescriptionSeverityAffected Software

Frequently Asked Questions

1

Which deployments are exposed to this issue?

Applications using aiohttp as an HTTP client are exposed when they process malformed responses from an attacker-controlled server. The issue can also be triggered by an accidental malformed response.

2

What must an attacker do to trigger the denial of service?

An attacker needs to cause the aiohttp client to parse a malformed response, including malformed chunked responses or malformed request or response bytes at the end of a buffer. The vulnerable code path is reached while constructing an error-message snippet in the C response parser.

3

What version resolves the issue?

The issue is fixed in aiohttp version 3.14.3. Versions prior to 3.14.3 are affected.

Contact

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