I dont know who needs to hear this bit qBittorrent has a nasty vulnerability ( and there are some older ones too)
qBittorrent, on all platforms, did not verify any SSL certificates in its DownloadManager class from 2010 until October 2024. If it failed to verify a cert, it simply logged an error and proceeded.
To be exploitable, this bug requires either MITM access or DNS spoofing attacks, but under those conditions (seen regularly in some countries), impacts are severe.
The primary impact is single-click RCE for Windows builds from 2015 onward, when prompted to update python the exe is downloaded from a hardcoded URL, executed, and then deleted afterwards.
The secondary impact for all platforms is the update RSS feed can be poisoned with malicious update URLs which the user will open in their browser if they accept the prompt to update. This is browser hijacking and arbitrary exe delivery to a user who would likely trust whatever URL this software sent them to.
The tertiary impact is this means that an older CVE (CVE-2019-13640 https://www.cvedetails.com/cve/CVE-2019-13640/) which allowed remote command execution via shell metacharacters could have been exploited by (government) attackers conducting either MITM or DNS spoofing attacks at the time, instead of only by the author of the feed.
Full write up is here: https://sharpsec.run/rce-vulnerability-in-qbittorrent/
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If you are running Windows […]
and
from June 2015 until the present, affecting v3.2.1 through v5.0.0 inclusive. The behaviour does not appear to be replicated for other OS variants
Will I be OK updating from the Debian repo?
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Is there something we should do in the meantime? I’m not the most savvy individual when it comes to tech on this level.
Not really. This requires a sophisticated attacker. I’d suggest updating soon but I doubt most people are at risk. As always verify downloads before running them and check where you should be getting updates and if you’re sent to a sketchy file hosted try to find updates from the official website instead.
The biggest risk is MTM interception and replacement of the python executable if you try and use the search tool for the first time. I suppose avoid doing that until you update the client from their website.
Thanks. This makes it a lot clearer.
Just update it to the latest
Ah. So this has already been addressed? Okay, thanks for responding.
Mitigations
Just use another torrent client. Deluge and Transmission etc do not have this vulnerability.
Was wondering what the takeaway is here. I updated to 5.0.1. Does that fix all these? If not, guess I’ll try a different torrent client.
The first patched release is version 5.0.1, released 2 days ago.
Containerization helps, but best to patch asap.