CVE-2023-49082

Improper validation makes it possible for an attacker to modify the HTTP request (e.g. insert a new header) or even create a new HTTP request if the attacker controls the HTTP method.

Details

The vulnerability occurs only if the attacker can control the HTTP method (GET, POST etc.) of the request.

Previous releases performed no validation on the provided value. If an attacker controls the HTTP method it will be used as is and can lead to HTTP request smuggling.

PoC

A minimal example can be found here:
https://gist.github.com/jnovikov/7f411ae9fe6a9a7804cf162a3bdbb44b

Workaround

If unable to upgrade and using user-provided values for the request method, perform manual validation of the user value (e.g. by restricting it to a few known values like GET, POST etc.).

Patch: https://github.com/aio-libs/aiohttp/pull/7806/files

If the attacker can control the HTTP version of the request it will be able to modify the request (request smuggling).

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2023-49082 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (3.9.0); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2023-49082? CVE-2023-49082 is a medium-severity improper input validation vulnerability in aiohttp (pip), affecting versions < 3.9.0. It is fixed in 3.9.0. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2023-49082? CVE-2023-49082 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of aiohttp are affected by CVE-2023-49082? aiohttp (pip) versions < 3.9.0 is affected.
4. Is there a fix for CVE-2023-49082? Yes. CVE-2023-49082 is fixed in 3.9.0. Upgrade to this version or later.
5. Is CVE-2023-49082 exploitable, and should I be worried? Whether CVE-2023-49082 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-49082 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-49082? Upgrade aiohttp to 3.9.0 or later.

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