CVE-2026-111748: AIOHTTP Absolute-Form Request Target Spoofing Vulnerability
Summary
CVE-2026-111748: AIOHTTP: Absolute-form request targets can spoof Request.scheme. Affects aiohttp versions < 3.14.4. Fixed in 3.14.4. How to fix ↓
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Background
AIOHTTP is a popular asynchronous HTTP client/server framework for Python, designed to handle asynchronous requests and responses efficiently. It is widely used in web applications for its ability to manage multiple connections concurrently. However, it has a vulnerability that allows attackers to send absolute-form requests that can spoof the Request.scheme attribute, potentially leading to security issues.
Vulnerability Detail
The vulnerability arises from the handling of absolute-form requests in AIOHTTP. An attacker can craft a request that manipulates the scheme used by the application, leading to a situation where the application may incorrectly assume a connection is secure (HTTPS) when it is not, or vice versa. This can result in unauthorized access or data exposure if the application relies on the Request.scheme for security decisions.
How To Fix
Latest published version: 3.14.5 as of 22 Oct 2026
pip install --upgrade "aiohttp==3.14.5"Upgrading to it may include breaking changes; the version below is the minimum fixed release for this vulnerability.
If you need the minimum change
3.14.4
This is the first release that contains the fix.
pip install --upgrade "aiohttp==3.14.4"Tip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary workaround, you can implement a Web Application Firewall (WAF) rule to reject absolute-form requests. This is particularly important as legitimate requests should only use this form for proxy purposes. Here is an example of a WAF rule that can be used:
if request.method == 'GET' and request.url.startswith('http://'):
reject_request()
This rule checks for GET requests and rejects those that use the HTTP scheme.
Conclusion
The AIOHTTP vulnerability identified as CVE-2026-111748 allows attackers to spoof the Request.scheme through absolute-form requests. It is crucial for developers using AIOHTTP to update to version 3.14.4 or later to mitigate this risk. Implementing a WAF rule can serve as a temporary workaround while the update is applied.
See every vulnerability recorded for aiohttp →
FAQ
The CVSS score of this vulnerability is 6.3, indicating a moderate severity level.
You can use the Vulert playground at Vulert Scanner to check if your application is affected by this vulnerability without requiring any signup.
If exploited, this vulnerability can lead to security breaches where an attacker can manipulate the perceived security of the connection, potentially exposing sensitive data.
Yes, version 3.14.4 and later of AIOHTTP has patched this vulnerability and is safe to use.
An absolute-form request is a type of HTTP request that includes the full URL, including the scheme (http or https), host, and path.
References
Related vulnerabilities
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