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PYSEC-2026-3431

MediumCVSS 6.1 / 10
Published Jul 13, 2026·Last modified Jul 13, 2026
Affected Components(0)

No affected components available

Description

Summary

If curl is used an external downloader for yt-dlp, cookies may be leaked to an unintended host upon HTTP redirect or when the host for download fragments differs from their parent manifest's.

This is the equivalent to GHSA-v8mc-9377-rwjj for the curl downloader. The vulnerable behavior is present in yt-dlp released since 2023.09.24.

Details

At the file download stage, the cookies are passed by yt-dlp to the file downloader via --cookie. However, unless these are loaded from a file, this operation does not activate the cookie engine. As a result, curl will send cookies with requests to domains or paths for which the cookies are not scoped.

An example of a potential attack scenario exploiting this vulnerability:

  1. an attacker has crafted a malicious website with an embedded URL designed to be detected by yt-dlp as a video download. This embedded URL has the domain of a trusted site that the user has loaded cookies for, and conducts an unvalidated redirect to a target URL.
  2. yt-dlp extracts this URL and calculates the cookies which are then passed to curl.
  3. the download URL redirects to a server controlled by the attacker, to which curl forwards the user's sensitive cookie information.

Patches

yt-dlp version 2026.06.09 fixes this issue by doing the following:

  • Pass the cookies through stdin via --cookie - if curl is version 7.59 or higher.
  • Pass the cookies via --cookie /dev/fd/0 if the system supports this device file.
  • In all other cases create a temporary file, save the cookies and then pass via --cookie <file>.

Workarounds

It is recommended to upgrade yt-dlp to version 2026.06.09 as soon as possible.

For users who are not able to upgrade:

  • Do not use --downloader curl.
Risk Scores
Base Score
6.1

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information.

Threat Intelligence
5.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.27%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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