### Impact
A leniency in h11's parsing of line terminators in chunked-coding message bodies can lead to request smuggling vulnerabilities under certain conditions.
### Details
HTTP/1.1 Chunked-Encoding bodies are formatted as a sequence of "chunks", each of which consists of:
- chunk length
- `\r\n`
- `length` bytes of content
- `\r\n`
In versions of h11 up to 0.14.0, h11 instead parsed them as:
- chunk length
- `\r\n`
- `length` bytes of content
- any two bytes
i.e. it did not validate that the trailing `\r\n` bytes were correct, and if you put 2 bytes of garbage there it would be accepted, instead of correctly rejecting the body as malformed.
By itself this is harmless. However, suppose you have a proxy or reverse-proxy that tries to analyze HTTP requests, and your proxy has a _different_ bug in parsing Chunked-Encoding, acting as if the format is:
- chunk length
- `\r\n`
- `length` bytes of content
- more bytes of content, as many as it takes until you find a `\r\n`
For example, [pound](https://github.com/graygnuorg/pound/pull/43) had this bug -- it can happen if an implementer uses a generic "read until end of line" helper to consumes the trailing `\r\n`.
In this case, h11 and your proxy may both accept the same stream of bytes, but interpret them differently. For example, consider the following HTTP request(s) (assume all line breaks are `\r\n`):
```
GET /one HTTP/1.1
Host: localhost
Transfer-Encoding: chunked
5
AAAAAXX2
45
0
GET /two HTTP/1.1
Host: localhost
Transfer-Encoding: chunked
0
```
Here h11 will interpret it as two requests, one with body `AAAAA45` and one with an empty body, while our hypothetical buggy proxy will interpret it as a single request, with body `AAAAXX20\r\n\r\nGET /two ...`. And any time two HTTP processors both accept the same string of bytes but interpret them differently, you have the conditions for a "request smuggling" attack. For example, if `/two` is a dangerous endpoint and the job of the reverse proxy is to stop requests from getting there, then an attacker could use a bytestream like the above to circumvent this protection.
Even worse, if our buggy reverse proxy receives two requests from different users:
```
GET /one HTTP/1.1
Host: localhost
Transfer-Encoding: chunked
5
AAAAAXX999
0
```
```
GET /two HTTP/1.1
Host: localhost
Cookie: SESSION_KEY=abcdef...
```
...it will consider the first request to be complete and valid, and send both on to the h11-based web server over the same socket. The server will then see the two concatenated requests, and interpret them as _one_ request to `/one` whose body includes `/two`'s session key, potentially allowing one user to steal another's credentials.
### Patches
Fixed in h11 0.15.0.
### Workarounds
Since exploitation requires the combination of buggy h11 with a buggy (reverse) proxy, fixing either component is sufficient to mitigate this issue.
### Credits
Reported by Jeppe Bonde Weikop on 2025-01-09.
A vulnerability in the `package_index` module of pypa/setuptools versions up to 69.1.1 allows for remote code execution via its download functions. These functions, which are used to download packages from URLs provided by users or retrieved from package index servers, are susceptible to code injection. If these functions are exposed to user-controlled inputs, such as package URLs, they can execute arbitrary commands on the system. The issue is fixed in version 70.0.
A Denial of Service (DoS) vulnerability exists in the jaraco/zipp library, affecting all versions prior to 3.19.1. The vulnerability is triggered when processing a specially crafted zip file that leads to an infinite loop. This issue also impacts the zipfile module of CPython, as features from the third-party zipp library are later merged into CPython, and the affected code is identical in both projects. The infinite loop can be initiated through the use of functions affecting the `Path` module in both zipp and zipfile, such as `joinpath`, the overloaded division operator, and `iterdir`. Although the infinite loop is not resource exhaustive, it prevents the application from responding. The vulnerability was addressed in version 3.19.1 of jaraco/zipp.
### Impact
Due to a URL parsing issue, Requests releases prior to 2.32.4 may leak .netrc credentials to third parties for specific maliciously-crafted URLs.
### Workarounds
For older versions of Requests, use of the .netrc file can be disabled with `trust_env=False` on your Requests Session ([docs](https://requests.readthedocs.io/en/latest/api/#requests.Session.trust_env)).
### References
https://github.com/psf/requests/pull/6965
https://seclists.org/fulldisclosure/2025/Jun/2