Affected: yt-dlp

yt-dlp is a command-line audio/video downloader. From 2023.09.24 until 2026.06.09, if curl is used as 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. 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. This vulnerability is fixed in 2026.06.09.

Affected: PyPI: yt-dlp

### 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](<https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-v8mc-9377-rwjj>) for the `curl` downloader. The vulnerable behavior is present in [yt-dlp](https://github.com/yt-dlp/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](https://cheatsheetseries.owasp.org/cheatsheets/Unvalidated_Redirects_and_Forwards_Cheat_Sheet.html) 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 thi…

Affected: PyPI: yt-dlp

### 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](<https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-v8mc-9377-rwjj>) for the `curl` downloader. The vulnerable behavior is present in [yt-dlp](https://github.com/yt-dlp/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](https://cheatsheetseries.owasp.org/cheatsheets/Unvalidated_Redirects_and_Forwards_Cheat_Sheet.html) 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 thi…