Update dependency aiohttp to v3.13.4 [SECURITY] by renovate[bot] · Pull Request #43 · practical-python-org/Hephaestus

renovate · 2025-12-10T10:49:41Z

ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package	Change	Age	Confidence
aiohttp	`==3.8.5` → `==3.13.4`

GitHub Vulnerability Alerts

CVE-2023-47627

Summary

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).

Details

Bug 1: Bad parsing of `Content-Length` values

Description

RFC 9110 says this:

Content-Length = 1*DIGIT

AIOHTTP does not enforce this rule, presumably because of an incorrect usage of the builtin int constructor. Because the int constructor accepts + and - prefixes, and digit-separating underscores, using int to parse CL values leads AIOHTTP to significant misinterpretation.

Examples

GET / HTTP/1.1\r\n
Content-Length: -0\r\n
\r\n
X

GET / HTTP/1.1\r\n
Content-Length: +0_1\r\n
\r\n
X

Suggested action

Verify that a Content-Length value consists only of ASCII digits before parsing, as the standard requires.

Bug 2: Improper handling of NUL, CR, and LF in header values

Description

RFC 9110 says this:

Field values containing CR, LF, or NUL characters are invalid and dangerous, due to the varying ways that implementations might parse and interpret those characters; a recipient of CR, LF, or NUL within a field value MUST either reject the message or replace each of those characters with SP before further processing or forwarding of that message.

AIOHTTP's HTTP parser does not enforce this rule, and will happily process header values containing these three forbidden characters without replacing them with SP.

Examples

GET / HTTP/1.1\r\n
Header: v\x00alue\r\n
\r\n

GET / HTTP/1.1\r\n
Header: v\ralue\r\n
\r\n

GET / HTTP/1.1\r\n
Header: v\nalue\r\n
\r\n

Suggested action

Reject all messages with NUL, CR, or LF in a header value. The translation to space thing, while technically allowed, does not seem like a good idea to me.

Bug 3: Improper stripping of whitespace before colon in HTTP headers

Description

RFC 9112 says this:

No whitespace is allowed between the field name and colon. In the past, differences in the handling of such whitespace have led to security vulnerabilities in request routing and response handling. A server MUST reject, with a response status code of 400 (Bad Request), any received request message that contains whitespace between a header field name and colon.

AIOHTTP does not enforce this rule, and will simply strip any whitespace before the colon in an HTTP header.

Example

GET / HTTP/1.1\r\n
Content-Length : 1\r\n
\r\n
X

Suggested action

Reject all messages with whitespace before a colon in a header field, as the standard requires.

PoC

Example requests are embedded in the previous section. To reproduce these bugs, start an AIOHTTP server without llhttp (i.e. AIOHTTP_NO_EXTENSIONS=1) and send the requests given in the previous section. (e.g. by printfing into nc)

Impact

Each of these bugs can be used for request smuggling.

GHSA-pjjw-qhg8-p2p9

Summary

llhttp 8.1.1 is vulnerable to two request smuggling vulnerabilities.
Details have not been disclosed yet, so refer to llhttp for future information.
The issue is resolved by using llhttp 9+ (which is included in aiohttp 3.8.6+).

CVE-2023-49082

Summary

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

Impact

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

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

CVE-2023-49081

Summary

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

Details

The vulnerability only occurs if the attacker can control the HTTP version of the request (including its type).
For example if an unvalidated JSON value is used as a version and the attacker is then able to pass an array as the version parameter.
Furthermore, the vulnerability only occurs when the Connection header is passed to the headers parameter.

At this point, the library will use the parsed value to create the request. If a list is passed, then it bypasses validation and it is possible to perform CRLF injection.

PoC

The POC below shows an example of providing an unvalidated array as a version:
https://gist.github.com/jnovikov/184afb593d9c2114d77f508e0ccd508e

Impact

CRLF injection leading to Request Smuggling.

Workaround

If these specific conditions are met and you are unable to upgrade, then validate the user input to the version parameter to ensure it is a str.

Patch: https://github.com/aio-libs/aiohttp/pull/7835/files

CVE-2024-23829

Summary

Security-sensitive parts of the Python HTTP parser retained minor differences in allowable character sets, that must trigger error handling to robustly match frame boundaries of proxies in order to protect against injection of additional requests. Additionally, validation could trigger exceptions that were not handled consistently with processing of other malformed input.

Details

These problems are rooted in pattern matching protocol elements, previously improved by PR #3235 and GHSA-gfw2-4jvh-wgfg:

The expression HTTP/(\d).(\d) lacked another backslash to clarify that the separator should be a literal dot, not just any Unicode code point (result: HTTP/(\d)\.(\d)).
The HTTP version was permitting Unicode digits, where only ASCII digits are standards-compliant.
Distinct regular expressions for validating HTTP Method and Header field names were used - though both should (at least) apply the common restrictions of rfc9110 token.

PoC

GET / HTTP/1ö1
GET / HTTP/1.𝟙
GET/: HTTP/1.1
Content-Encoding?: chunked

Impact

Primarily concerns running an aiohttp server without llhttp:

behind a proxy: Being more lenient than internet standards require could, depending on deployment environment, assist in request smuggling.
directly accessible or exposed behind proxies relaying malformed input: the unhandled exception could cause excessive resource consumption on the application server and/or its logging facilities.

Patch: https://github.com/aio-libs/aiohttp/pull/8074/files

CVE-2024-23334

Summary

Improperly configuring static resource resolution in aiohttp when used as a web server can result in the unauthorized reading of arbitrary files on the system.

Details

When using aiohttp as a web server and configuring static routes, it is necessary to specify the root path for static files. Additionally, the option 'follow_symlinks' can be used to determine whether to follow symbolic links outside the static root directory. When 'follow_symlinks' is set to True, there is no validation to check if a given file path is within the root directory.This can lead to directory traversal vulnerabilities, resulting in unauthorized access to arbitrary files on the system, even when symlinks are not present.

i.e. An application is only vulnerable with setup code like:

app.router.add_routes([
    web.static("/static", "static/", follow_symlinks=True),  # Remove follow_symlinks to avoid the vulnerability
])

Impact

This is a directory traversal vulnerability with CWE ID 22. When using aiohttp as a web server and enabling static resource resolution with follow_symlinks set to True, it can lead to this vulnerability. This vulnerability has been present since the introduction of the follow_symlinks parameter.

Workaround

Even if upgrading to a patched version of aiohttp, we recommend following these steps regardless.

If using follow_symlinks=True outside of a restricted local development environment, disable the option immediately. This option is NOT needed to follow symlinks which point to a location within the static root directory, it is only intended to allow a symlink to break out of the static directory. Even with this CVE fixed, there is still a substantial risk of misconfiguration when using this option on a server that accepts requests from remote users.

Additionally, aiohttp has always recommended using a reverse proxy server (such as nginx) to handle static resources and not to use these static resources in aiohttp for production environments. Doing so also protects against this vulnerability, and is why we expect the number of affected users to be very low.

Patch: https://github.com/aio-libs/aiohttp/pull/8079/files

CVE-2024-27306

Summary

A XSS vulnerability exists on index pages for static file handling.

Details

When using web.static(..., show_index=True), the resulting index pages do not escape file names.

If users can upload files with arbitrary filenames to the static directory, the server is vulnerable to XSS attacks.

Workaround

We have always recommended using a reverse proxy server (e.g. nginx) for serving static files. Users following the recommendation are unaffected.

Other users can disable show_index if unable to upgrade.

Patch: https://github.com/aio-libs/aiohttp/pull/8319/files

CVE-2024-30251

Summary

An attacker can send a specially crafted POST (multipart/form-data) request. When the aiohttp server processes it, the server will enter an infinite loop and be unable to process any further requests.

Impact

An attacker can stop the application from serving requests after sending a single request.

For anyone needing to patch older versions of aiohttp, the minimum diff needed to resolve the issue is (located in _read_chunk_from_length()):

diff --git a/aiohttp/multipart.py b/aiohttp/multipart.py
index 227be605c..71fc2654a 100644
--- a/aiohttp/multipart.py
+++ b/aiohttp/multipart.py
@&#8203;@&#8203; -338,6 +338,8 @&#8203;@&#8203; class BodyPartReader:
         assert self._length is not None, "Content-Length required for chunked read"
         chunk_size = min(size, self._length - self._read_bytes)
         chunk = await self._content.read(chunk_size)
+        if self._content.at_eof():
+            self._at_eof = True
         return chunk
 
     async def _read_chunk_from_stream(self, size: int) -> bytes:

This does however introduce some very minor issues with handling form data. So, if possible, it would be recommended to also backport the changes in:
aio-libs/aiohttp@cebe526
aio-libs/aiohttp@7eecdff
aio-libs/aiohttp@f21c6f2

CVE-2024-52304

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 AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.

Patch: aio-libs/aiohttp@259edc3

CVE-2025-53643

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 AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.

Patch: aio-libs/aiohttp@e8d774f

CVE-2025-69224

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 AIOHTTP_NO_EXTENSIONS is enabled, then an attacker may be able to execute a request smuggling attack to bypass certain firewalls or proxy protections.

Patch: aio-libs/aiohttp@32677f2

CVE-2025-69223

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.

Patch: aio-libs/aiohttp@2b920c3

CVE-2025-69225

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.

Patch: aio-libs/aiohttp@c7b7a04

CVE-2025-69226

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.

Patch: aio-libs/aiohttp@f2a86fd

CVE-2025-69227

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.

Patch: aio-libs/aiohttp@bc1319e

CVE-2025-69228

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.

Patch: aio-libs/aiohttp@b7dbd35

CVE-2025-69230

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.

Patch: aio-libs/aiohttp@64629a0

CVE-2025-69229

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.

Patch: aio-libs/aiohttp@dc3170b
Patch: aio-libs/aiohttp@4ed97a4

CVE-2026-22815

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.

Patch: aio-libs/aiohttp@0c2e9da

CVE-2026-34513

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.

Patch: aio-libs/aiohttp@c4d77c3

CVE-2026-34514

Summary

An attacker who controls the content_type 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 content_type parameter when constructing a request, an attacker may be able to manipulate the request to send something other than what the developer intended.

Patch: aio-libs/aiohttp@9a6ada9

CVE-2026-34515

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.

Patch: aio-libs/aiohttp@0ae2aa0

CVE-2026-34516

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.

Patch: aio-libs/aiohttp@8a74257

CVE-2026-34517

Summary

For some multipart form fields, aiohttp read the entire field into memory before checking client_max_size.

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.

Patch: aio-libs/aiohttp@cbb774f

CVE-2026-34518

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.

Patch: aio-libs/aiohttp@5351c98

CVE-2026-34519

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.

Patch: aio-libs/aiohttp@53b35a2

CVE-2026-34520

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.

Patch: aio-libs/aiohttp@9370b97

CVE-2026-34525

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.add_domain().

Patch: aio-libs/aiohttp@e00ca3c
Patch: aio-libs/aiohttp@53e2e6f

Release Notes

aio-libs/aiohttp (aiohttp)

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GitHub Vulnerability Alerts

Summary

Details

Bug 1: Bad parsing of Content-Length values

Description

Examples

Suggested action

Bug 2: Improper handling of NUL, CR, and LF in header values

Description

Examples

Suggested action

Bug 3: Improper stripping of whitespace before colon in HTTP headers

Description

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renovate bot commented Dec 10, 2025 •

edited

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Bug 1: Bad parsing of `Content-Length` values

`v3.13.2`: 3.13.2