CVE-2026-34518
Received Received - Intake
Authorization Header Disclosure in aiohttp Redirect Handling Prior to

Publication date: 2026-04-01

Last updated on: 2026-04-16

Assigner: GitHub, Inc.

Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, when following redirects to a different origin, aiohttp drops the Authorization header, but retains the Cookie and Proxy-Authorization headers. This issue has been patched in version 3.13.4.
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Meta Information
Published
2026-04-01
Last Modified
2026-04-16
Generated
2026-06-16
AI Q&A
2026-04-02
EPSS Evaluated
2026-06-15
NVD
CVE-2026-34518
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
aiohttp aiohttp to 3.13.4 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
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Executive Summary

This vulnerability exists in the aiohttp framework prior to version 3.13.4. When aiohttp follows HTTP redirects to a different origin, it incorrectly drops the Authorization header while still retaining the Cookie and Proxy-Authorization headers.

This behavior can lead to unintended loss of authorization credentials during redirects, potentially affecting authentication flows.

The issue has been fixed in version 3.13.4 of aiohttp.

Impact Analysis

The impact of this vulnerability is that when an application using aiohttp follows redirects to a different origin, the Authorization header is dropped.

This could cause authentication failures or unexpected behavior in applications relying on the Authorization header for access control during redirects.

Since the Cookie and Proxy-Authorization headers are retained, some credentials may still be sent, but the loss of the Authorization header could lead to security or functionality issues depending on the application's design.

Mitigation Strategies

To mitigate this vulnerability, upgrade aiohttp to version 3.13.4 or later, where the issue has been patched.

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