CVE-2023-35934 | yt-dlp File Downloader cookie leak

yt-dlp is a command-line program to download videos from video sites. During 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. This vulnerable behavior is present in yt-dlp prior to 2023.07.06 and nightly 2023.07.06.185519. All native and external downloaders are affected, except for `curl` and `httpie` (version 3.1.0 or later). At 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. yt-dlp version 2023.07.06 and nightly 2023.07.06.185519 fix this issue by removing the `Cookie` header upon HTTP redirects; having native downloaders calculate the `Cookie` header from the cookiejar, utilizing external downloaders' built-in support for cookies instead of passing them as header arguments, disabling HTTP redirectiong if the external downloader does not have proper cookie support, processing cookies passed as HTTP headers to limit their scope, and having a separate field for cookies in the info dict storing more information about scoping Some workarounds are available for those who are unable to upgrade. Avoid using cookies and user authentication methods. While extractors may set custom cookies, these usually do not contain sensitive information. Alternatively, avoid using `--load-info-json`. Or, if authentication is a must: verify the integrity of download links from unknown sources in browser (including redirects) before passing them to yt-dlp; use `curl` as external downloader, since it is not impacted; and/or avoid fragmented formats such as HLS/m3u8, DASH/mpd and ISM.

Published: 2023-07-06 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]

Conclusion & alert: CVE-2023-35934 is rated Moderate Risk (49.6/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 0.69%). Mandatory action: Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2023-35934

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-02 0.65% 0.69% +0.04%
2 2026-01-02 0.48% 0.65% +0.17%
3 2025-11-21 0.48%

Full EPSS history (18 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2023-35934

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.1 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
1.6 4.0 [email protected]
8.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
2.8 4.7 [email protected]

Weakness enumeration for CVE-2023-35934

GitHub Security Advisory for CVE-2023-35934

GHSA-v8mc-9377-rwjj · Severity: medium · Ecosystem: pip — yt-dlp File Downloader cookie leak

OS Trackers for CVE-2023-35934

vendor priority summary link
alpine high CVE-2023-35934: 1 source package rows (yt-dlp); 10 state rows across 6 repos (3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 8, open 2. https://security.alpinelinux.org/vuln/CVE-2023-35934
debian not yet assigned CVE-2023-35934 not yet assigned priority: Debian including 2 source packages (youtube-dl, yt-dlp), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 3. https://security-tracker.debian.org/tracker/CVE-2023-35934
gentoo normal CVE-2023-35934: 1 GLSA(s) (202409-30), 1 atom(s) (net-misc/yt-dlp); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2023-35934
ubuntu medium CVE-2023-35934 medium priority: Ubuntu including 1 source packages (yt-dlp), 13 status rows across 13 suites (bionic, focal, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): ignored 8, needs-triage 4, DNE 1. https://ubuntu.com/security/CVE-2023-35934

Affected software / configurations for CVE-2023-35934

Vendor Product Version Raw CPE
youtube-dlc_project youtube-dlc cpe:2.3:a:youtube-dlc_project:youtube-dlc:*:*:*:*:*:*:*:*
yt-dl youtube-dl >= 2015.01.25 cpe:2.3:a:yt-dl:youtube-dl:*:*:*:*:*:*:*:*
yt-dlp_project yt-dlp < 2023.07.06 cpe:2.3:a:yt-dlp_project:yt-dlp:*:*:*:*:-:*:*:*
yt-dlp_project yt-dlp < 2023.07.06.185519 cpe:2.3:a:yt-dlp_project:yt-dlp:*:*:*:*:nightly:*:*:*
fedoraproject fedora 37 cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*
fedoraproject fedora 38 cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*

References for CVE-2023-35934

URL Tags
https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.07.06.185519 Release Notes
https://github.com/yt-dlp/yt-dlp/commit/1ceb657bdd254ad961489e5060f2ccc7d556b729 Patch
https://github.com/yt-dlp/yt-dlp/commit/3121512228487c9c690d3d39bfd2579addf96e07 Patch
https://github.com/yt-dlp/yt-dlp/commit/f8b4bcc0a791274223723488bfbfc23ea3276641 Patch
https://github.com/yt-dlp/yt-dlp/releases/tag/2023.07.06 Release Notes
https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-v8mc-9377-rwjj Vendor Advisory
https://lists.fedoraproject.org/archives/list/[email protected]/message/5X6YT6AQE5FHM5VTQLKKJXSYBLLJF26W/ Mailing List
https://lists.fedoraproject.org/archives/list/[email protected]/message/HEOKCGVONGHR2SYUIXU33A4MKXZBDP6L/
https://lists.fedoraproject.org/archives/list/[email protected]/message/IM44RJL2MR2WG3ZY354C5IUEEZUJGEVA/ Mailing List
https://lists.fedoraproject.org/archives/list/[email protected]/message/M7E7CQ5S5KMZHAMCNU7V7KYNBVCPLBHG/
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