See how aiohttp compares to other vendors in security performance
Summary A zip bomb can be used to execute a DoS against the aiohttp server.
Impact An attacker may be able to send a compressed request that when decompressed by aiohttp could exhaust the host's memory.
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Patch: https://github.com/aio-libs/aiohttp/commit/2b920c39002cee0ec5b402581779bbaaf7c9138a
Summary The Python HTTP parser may allow a request smuggling attack with the presence of non-ASCII characters.
Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.
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Patch: https://github.com/aio-libs/aiohttp/commit/32677f2adfd907420c078dda6b79225c6f4ebce0
Summary Path normalization for static files prevents path traversal, but opens up the ability for an attacker to ascertain the existence of absolute path components.
Impact If an application uses web.static() (not recommended for production deployments), it may be possible for an attacker to ascertain the existence of path components.
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Patch: https://github.com/aio-libs/aiohttp/commit/f2a86fd5ac0383000d1715afddfa704413f0711e
Summary
The parser allows non-ASCII decimals to be present in the Range header.
Impact
There is no known impact, but there is the possibility that there's a method to exploit a request smuggling vulnerability.
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Patch: https://github.com/aio-libs/aiohttp/commit/c7b7a044f88c71cefda95ec75cdcfaa4792b3b96
Summary When assert statements are bypassed, an infinite loop can occur, resulting in a DoS attack when processing a POST body.
Impact If optimisations are enabled (-O or PYTHONOPTIMIZE=1), and the application includes a handler that uses the Request.post() method, then an attacker may be able to execute a DoS attack with a specially crafted message.
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Patch: https://github.com/aio-libs/aiohttp/commit/bc1319ec3cbff9438a758951a30907b072561259
Summary A request can be crafted in such a way that an aiohttp server's memory fills up uncontrollably during processing.
Impact If an application includes a handler that uses the Request.post() method, an attacker may be able to freeze the server by exhausting the memory.
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Patch: https://github.com/aio-libs/aiohttp/commit/b7dbd35375aedbcd712cbae8ad513d56d11cce60
Summary
Handling of chunked messages can result in excessive blocking CPU usage when receiving a large number of chunks.
Impact
If an application makes use of the request.read() method in an endpoint, it may be possible for an attacker to cause the server to spend a moderate amount of blocking CPU time (e.g. 1 second) while processing the request. This could potentially lead to DoS as the server would be unable to handle other requests during that time.
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Patch: https://github.com/aio-libs/aiohttp/commit/dc3170b56904bdf814228fae70a5501a42a6c712 Patch: https://github.com/aio-libs/aiohttp/commit/4ed97a4e46eaf61bd0f05063245f613469700229
Summary Reading multiple invalid cookies can lead to a logging storm.
Impact If the cookies attribute is accessed in an application, then an attacker may be able to trigger a storm of warning-level logs using a specially crafted Cookie header.
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Patch: https://github.com/aio-libs/aiohttp/commit/64629a0834f94e46d9881f4e99c41a137e1f3326
Summary
Insufficient restrictions in header/trailer handling could cause uncapped memory usage.
Impact
An application could cause memory exhaustion when receiving an attacker controlled request or response. A vulnerable web application could mitigate these risks with a typical reverse proxy configuration.
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Patch: https://github.com/aio-libs/aiohttp/commit/0c2e9da51126238a421568eb7c5b53e5b5d17b36
Summary
For some multipart form fields, aiohttp read the entire field into memory before checking clientmaxsize.
Impact
If an application uses Request.post() an attacker can send a specially crafted multipart request to force significant temporary memory allocation even when the request is ultimately rejected.
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Patch: https://github.com/aio-libs/aiohttp/commit/cbb774f38330563422ca0c413a71021d7b944145
Summary
An attacker who controls the contenttype parameter in aiohttp could use this to inject extra headers or similar exploits.
Impact
If an application allows untrusted data to be used for the multipart contenttype parameter when constructing a request, an attacker may be able to manipulate the request to send something other than what the developer intended.
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Patch: https://github.com/aio-libs/aiohttp/commit/9a6ada97e2c6cf1ce31727c6c9fcea17c21f6f06
Summary
An unbounded DNS cache could result in excessive memory usage possibly resulting in a DoS situation.
Impact
If an application makes requests to a very large number of hosts, this could cause the DNS cache to continue growing and slowly use excessive amounts of memory.
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Patch: https://github.com/aio-libs/aiohttp/commit/c4d77c3533122be353b8afca8e8675e3b4cbda98
Summary
When following redirects to a different origin, aiohttp drops the Authorization header, but retains the Cookie and Proxy-Authorization headers.
Impact
The Cookie and Proxy-Authorizations headers could contain sensitive information which may be leaked to an unintended party after following a redirect.
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Patch: https://github.com/aio-libs/aiohttp/commit/5351c980dcec7ad385730efdf4e1f4338b24fdb6
Summary
On Windows the static resource handler may expose information about a NTLMv2 remote path.
Impact
If an application is running on Windows, and using aiohttp's static resource handler (not recommended in production), then it may be possible for an attacker to extract the hash from an NTLMv2 path and then extract the user's credentials from there.
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Patch: https://github.com/aio-libs/aiohttp/commit/0ae2aa076c84573df83fc1fdc39eec0f5862fe3d
Summary
A response with an excessive number of multipart headers may be allowed to use more memory than intended, potentially allowing a DoS vulnerability.
Impact
Multipart headers were not subject to the same size restrictions in place for normal headers, potentially allowing substantially more data to be loaded into memory than intended. However, other restrictions in place limit the impact of this vulnerability.
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Patch: https://github.com/aio-libs/aiohttp/commit/8a74257b3804c9aac0bf644af93070f68f6c5a6f
Summary
Multiple Host headers were allowed in aiohttp.
Impact
Mostly this doesn't affect aiohttp security itself, but if a reverse proxy is applying security rules depending on the target Host, it is theoretically possible that the proxy and aiohttp could process different host names, possibly resulting in bypassing a security check on the proxy and getting a request processed by aiohttp in a privileged sub app when using Application.adddomain().
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Patch: https://github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349 Patch: https://github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000
Summary
The C parser (the default for most installs) accepted null bytes and control characters is response headers.
Impact
An attacker could send header values that are interpreted differently than expected due to the presence of control characters. For example, request.url.origin() may return a different value than the raw Host header, or what a reverse proxy interpreted it as., potentially resulting in some kind of security bypass.
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Patch: https://github.com/aio-libs/aiohttp/commit/9370b9714a7a56003cacd31a9b4ae16eab109ba4
Summary
An attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits.
Impact
In the unlikely situation that an application allows untrusted data to be used in the response's reason parameter, then an attacker could manipulate the response to send something different from what the developer intended.
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Patch: https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b
Summary
DigestAuthMiddleware can send an authentication response after following a cross-origin redirect.
Impact
If the client follows a redirect (the default option) to an attacker controlled domain, the attacker may be able to extract the auth digest.
This likely requires an open redirect vulnerability or similar on the target domain for an attacker to be able to execute. Further, the attacker is only receiving the digest, so should only be able to extract the user's credentials if the cryptography is weak or there is some kind of password reuse.
Workaround
Disable followredirects if this is a concern.
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Patch: https://github.com/aio-libs/aiohttp/commit/38d16060037e1bfcd6d677abababa3c2a4bb58fa
Summary
Using CookieJar.load() with untrusted input may allow arbitrary code execution.
Impact
Most applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications.
Workaround
If an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitise the files before loading.
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Patch: https://github.com/aio-libs/aiohttp/commit/dcf40f30637e8752c76781cf6703b5a236749a00
Summary
Payload resources are not closed correctly when a client disconnects in the middle of a write.
Impact
If a payload is using an open file or similar limited resource, then an attacker may be able to cause resource starvation temporarily until garbage collection or similar closes the file.
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Patch: https://github.com/aio-libs/aiohttp/commit/a762eda5242f6490d6ba667533193f8b473ad587
Summary
An out-of-bounds heap read could occur in the C response parser while building an error message for a malformed response.
Impact
An attacker controlled server, or possibly an accidental response could trigger a DoS in the client.
Workaround
If unable to upgrade, the Python parser is unaffected and can be used with AIOHTTPNOEXTENSIONS=1.
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Patch: https://github.com/aio-libs/aiohttp/commit/49f65d54150397892f7bcc4aae887767d51c322d
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.14.0, using CookieJar.load() with untrusted input may allow arbitrary code execution. Most applications using this function will be doing so with the user's own data, so this is unlikely to affect many applications. Version 3.14.0 patches the issue. If an application does allow attacker controlled files to be loaded, a workaround on older releases would be to sanitize the files before loading.
Summary The Python parser is vulnerable to a request smuggling vulnerability due to not parsing trailer sections of an HTTP request.
Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.
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Patch: https://github.com/aio-libs/aiohttp/commit/e8d774f635dc6d1cd3174d0e38891da5de0e2b6a
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.
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the HTTP parsers were vulnerable to a request smuggling attack relating to WebSocket upgrades. If using the server-side component, an attacker may be able to execute a request smuggling vulnerability using an edge case in the WebSocket upgrade procedure. A WebSocket upgrade request with a body could cause the parser to switch protocols before the complete request body was received, leaving trailing bytes to be handled as upgraded-protocol or pipelined data rather than normal HTTP body data. This issue is fixed in version 3.14.2.
Impact
aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6 which is vulnerable to CVE-2023-30589. The 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).
Reproducer
python from aiohttp import web
async def example(request: web.Request): headers = dict(request.headers) body = await request.content.read() return web.Response(text=f"headers: {headers} body: {body}")
app = web.Application() app.addroutes([web.post('/', example)]) web.runapp(app)
Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling.
console $ printf "POST / HTTP/1.1\r\nHost: localhost:8080\r\nX-Abc: \rxTransfer-Encoding: chunked\r\n\r\n1\r\nA\r\n0\r\n\r\n" \ | nc localhost 8080
Expected output: headers: {'Host': 'localhost:8080', 'X-Abc': '\rxTransfer-Encoding: chunked'} body: b''
Actual output (note that 'Transfer-Encoding: chunked' is an HTTP header now and body is treated differently) headers: {'Host': 'localhost:8080', 'X-Abc': '', 'Transfer-Encoding': 'chunked'} body: b'A'
Patches
Upgrade to the latest version of aiohttp to resolve this vulnerability. It has been fixed in v3.8.5: pip install aiohttp >= 3.8.5
Workarounds
If you aren't able to upgrade you can reinstall aiohttp using AIOHTTPNOEXTENSIONS=1 as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable to request smuggling:
console $ python -m pip uninstall --yes aiohttp $ AIOHTTPNOEXTENSIONS=1 python -m pip install --no-binary=aiohttp --no-cache aiohttp
References
https://nvd.nist.gov/vuln/detail/CVE-2023-30589 https://hackerone.com/reports/2001873
Summary The Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions.
Impact If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.
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Patch: https://github.com/aio-libs/aiohttp/commit/259edc369075de63e6f3a4eaade058c62af0df71
aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.10.11, the Python parser parses newlines in chunk extensions incorrectly which can lead to request smuggling vulnerabilities under certain conditions. If a pure Python version of aiohttp is installed (i.e. without the usual C extensions) or AIOHTTPNOEXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections. Version 3.10.11 fixes the issue.
Summary
The client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated.
Impact
A client may unexpectedly decompress WebSocket frames when explicitly opted out. This could lead to additional CPU/memory consumption, but is unlikely to be a significant issue unless a zip bomb vulnerability or similar is also present.
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Patch: https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6