aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. The HTTP parser in AIOHTTP has numerous problems with header parsing, which could lead to request smuggling. This parser is only used when AIOHTTP_NO_EXTENSIONS is enabled (or not using a prebuilt wheel). These bugs have been addressed in commit `d5c12ba89` which has been included in release version 3.8.6. Users are advised to upgrade. There are no known workarounds for these issues.

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6. Vulnerable code is used by aiohttp for its HTTP request parser when available which is the default case when installing from a wheel. This vulnerability only affects users of aiohttp as an HTTP server (ie `aiohttp.Application`), you are not affected by this vulnerability if you are using aiohttp as an HTTP client library (ie `aiohttp.ClientSession`). Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling. This issue has been addressed in version 3.8.5. Users are advised to upgrade. Users unable to upgrade can reinstall aiohttp using `AIOHTTP_NO_EXTENSIONS=1` as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable.

AIOHTTP 3.8.1 can report a "ValueError: Invalid IPv6 URL" outcome, which can lead to a Denial of Service (DoS). NOTE: multiple third parties dispute this issue because there is no example of a context in which denial of service would occur, and many common contexts have exception handing in the calling application

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. In aiohttp before version 3.7.4 there is an open redirect vulnerability. A maliciously crafted link to an aiohttp-based web-server could redirect the browser to a different website. It is caused by a bug in the `aiohttp.web_middlewares.normalize_path_middleware` middleware. This security problem has been fixed in 3.7.4. Upgrade your dependency using pip as follows "pip install aiohttp >= 3.7.4". If upgrading is not an option for you, a workaround can be to avoid using `aiohttp.web_middlewares.normalize_path_middleware` in your applications.

aio-libs aiohttp-session version 2.6.0 and earlier contains a Other/Unknown vulnerability in EncryptedCookieStorage and NaClCookieStorage that can result in Non-expiring sessions / Infinite lifespan. This attack appear to be exploitable via Recreation of a cookie post-expiry with the same value.

aio-libs aiohttp-session contains a Session Fixation vulnerability in load_session function for RedisStorage (see: https://github.com/aio-libs/aiohttp-session/blob/master/aiohttp_session/redis_storage.py#L42) that can result in Session Hijacking. This attack appear to be exploitable via Any method that allows setting session cookies (?session=<>, or meta tags or script tags with Set-Cookie).