{"id":"CVE-2023-35934","aliases":["GHSA-v8mc-9377-rwjj","PYSEC-2026-2067"],"url":"https://o3.security/vulnerability/CVE-2023-35934","summary":"yt-dlp File Downloader cookie leak","details":"### Impact\nDuring file downloads, yt-dlp or the external downloaders that yt-dlp employs may leak cookies on HTTP redirects to a different host, or leak them when the host for download fragments differs from their parent manifest's host.\n\nThis vulnerable behavior is present in all versions of [youtube-dl](https://github.com/ytdl-org/youtube-dl), [youtube-dlc](https://github.com/blackjack4494/yt-dlc) and [yt-dlp](https://github.com/yt-dlp/yt-dlp) released since 2015.01.25. All native and external downloaders are affected, except for `curl` and `httpie` (httpie version 3.1.0 or later).\n\nAt the file download stage, all cookies are passed by yt-dlp to the file downloader as a `Cookie` header, thereby losing their scope. This also occurs in yt-dlp's info JSON output, which may be used by external tools. As a result, the downloader or external tool may indiscriminately send cookies with requests to domains or paths for which the cookies are not scoped.\n\nAn example of a potential attack scenario exploiting this vulnerability:\n1. 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.\n2. yt-dlp extracts this URL and calculates a `Cookie` header based on its domain for the file downloader to make its request(s) with.\n3. the download URL redirects to a server controlled by the attacker, to which yt-dlp forwards the user's sensitive cookie information.\n\n### Patches\nyt-dlp version 2023.07.06 fixes this issue by doing the following:\n\n- Remove the `Cookie` header upon HTTP redirects\n- Have native downloaders calculate their own `Cookie` header from the cookiejar\n- Utilize external downloaders' built-in support for cookies instead of passing them as header arguments\n- If the external downloader does not have proper cookie support, then disable HTTP redirection (`axel` only)\n- Process cookies passed as HTTP headers to limit their scope (`--add-header \"Cookie:...\"` is scoped to input URL domain only)\n- Store cookies in a separate `cookies` field of the info dict instead of `http_headers` so as not to lose their scope\n\nPatches for youtube-dl are expected and we will update this advisory when they are merged.\n\n### Workarounds\nIt is recommended to upgrade yt-dlp to version 2023.07.06 as soon as possible.\n\nFor users who are not able to upgrade:\n\n - Avoid using cookies and user authentication methods (`--cookies`, `--cookies-from-browser`, `--username`, `--password`, `--netrc`). While extractors may set custom cookies, these usually do not contain sensitive information.\n - Avoid using `--load-info-json`\n\nOr, if authentication is a must:\n\n- Verify the integrity of download links from unknown sources in browser (including redirects) before passing them to yt-dlp\n- Use `curl` as external downloader, since it is not impacted (`--downloader curl`)\n- Avoid fragmented formats such as HLS/m3u8, DASH/mpd and ISM (use `-f \"(bv*+ba/b)[protocol~='^https?$']\"`)\n\n### References\n- https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-v8mc-9377-rwjj\n- https://nvd.nist.gov/vuln/detail/CVE-2023-35934\n- https://github.com/yt-dlp/yt-dlp/releases/tag/2023.07.06\n- https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.07.06.185519\n- https://github.com/yt-dlp/yt-dlp/commit/1ceb657bdd254ad961489e5060f2ccc7d556b729\n- https://github.com/yt-dlp/yt-dlp/commit/f8b4bcc0a791274223723488bfbfc23ea3276641\n- https://github.com/yt-dlp/yt-dlp/commit/3121512228487c9c690d3d39bfd2579addf96e07","published":"2023-07-06T19:39:49.656Z","modified":"2026-10-28T02:30:56.671517181Z","cvss":{"score":6.1,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"yt-dlp","fixedVersion":"2023.7.06"}],"fix":{"url":"https://github.com/yt-dlp/yt-dlp/commit/1ceb657bdd254ad961489e5060f2ccc7d556b729","label":"yt-dlp/yt-dlp@1ceb657"},"references":[{"type":"WEB","url":"https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.07.06.185519"},{"type":"WEB","url":"https://github.com/yt-dlp/yt-dlp/releases/tag/2023.07.06"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5X6YT6AQE5FHM5VTQLKKJXSYBLLJF26W/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HEOKCGVONGHR2SYUIXU33A4MKXZBDP6L/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IM44RJL2MR2WG3ZY354C5IUEEZUJGEVA/"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/M7E7CQ5S5KMZHAMCNU7V7KYNBVCPLBHG/"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/35xxx/CVE-2023-35934.json"},{"type":"ADVISORY","url":"https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-v8mc-9377-rwjj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-35934"},{"type":"FIX","url":"https://github.com/yt-dlp/yt-dlp/commit/1ceb657bdd254ad961489e5060f2ccc7d556b729"},{"type":"FIX","url":"https://github.com/yt-dlp/yt-dlp/commit/3121512228487c9c690d3d39bfd2579addf96e07"},{"type":"FIX","url":"https://github.com/yt-dlp/yt-dlp/commit/f8b4bcc0a791274223723488bfbfc23ea3276641"},{"type":"PACKAGE","url":"https://github.com/yt-dlp/yt-dlp"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/5X6YT6AQE5FHM5VTQLKKJXSYBLLJF26W"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HEOKCGVONGHR2SYUIXU33A4MKXZBDP6L"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/IM44RJL2MR2WG3ZY354C5IUEEZUJGEVA"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/M7E7CQ5S5KMZHAMCNU7V7KYNBVCPLBHG"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:30:56.671517181Z"}}