CVE-2023-40581

Workarounds

It is recommended to upgrade yt-dlp to version 2023.09.24 as soon as possible. Also, always be careful when using --exec, because while this specific vulnerability has been patched, using unvalidated input in shell commands is inherently dangerous.

For Windows users who are not able to upgrade:

• Avoid using any output template expansion in --exec other than {} (filepath).
• If expansion in --exec is needed, verify the fields you are using do not contain ", | or &.
• Instead of using --exec, write the info json and load the fields from it instead.

References

• https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-42h4-v29r-42qg
• https://nvd.nist.gov/vuln/detail/CVE-2023-40581
• https://github.com/yt-dlp/yt-dlp/releases/tag/2023.09.24
• https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.09.24.003044
• https://github.com/yt-dlp/yt-dlp/commit/de015e930747165dbb8fcd360f8775fd973b7d6e

yt-dlp allows the user to provide shell commands to be executed at various stages in its download process through the --exec flag. This flag allows output template expansion in its argument, so that video metadata values may be used in the shell commands. The metadata fields can be combined with the %q conversion, which is intended to quote/escape these values so they can be safely passed to the shell.

However, the escaping used for cmd (the shell used by Python's subprocess on Windows) did not properly escape special characters, which can allow for remote code execution if --exec is used directly with maliciously crafted remote data. This vulnerability only impacts yt-dlp on Windows, and the vulnerability is present regardless of whether yt-dlp is run from cmd or from PowerShell.

Support for output template expansion in --exec, along with this vulnerable behavior, was added to yt-dlp in version 2021.04.11.

> yt-dlp https://youtu.be/Jo66yyCpHcQ --exec "echo %(title)q"
[youtube] Extracting URL: https://youtu.be/Jo66yyCpHcQ
[youtube] Jo66yyCpHcQ: Downloading webpage
[youtube] Jo66yyCpHcQ: Downloading ios player API JSON
[youtube] Jo66yyCpHcQ: Downloading android player API JSON
[youtube] Jo66yyCpHcQ: Downloading m3u8 information
[info] Jo66yyCpHcQ: Downloading 1 format(s): 135+251
[download] Destination: ＂&echo(&echo(pwned&rem( [Jo66yyCpHcQ].f135.mp4
[download] 100% of    4.85KiB in 00:00:00 at 60.20KiB/s
[download] Destination: ＂&echo(&echo(pwned&rem( [Jo66yyCpHcQ].f251.webm
[download] 100% of    4.80KiB in 00:00:00 at 31.58KiB/s
[Merger] Merging formats into "＂&echo(&echo(pwned&rem( [Jo66yyCpHcQ].mkv"
Deleting original file ＂&echo(&echo(pwned&rem( [Jo66yyCpHcQ].f135.mp4 (pass -k to keep)
Deleting original file ＂&echo(&echo(pwned&rem( [Jo66yyCpHcQ].f251.webm (pass -k to keep)
[Exec] Executing command: echo "\"&echo(&echo(pwned&rem("
"\"

pwned

Untrusted input reaches a shell command, allowing arbitrary commands to run on the host. Typical impact: code execution in the application's environment.

CVE-2023-40581 has a CVSS score of 8.3 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2023.09.24); upgrading removes the vulnerable code path.

Kodem intelligence

yt-dlp version 2023.09.24 fixes this issue by properly escaping each special character.
\n will be replaced by \r, as no way of escaping it has been found.

1. What is CVE-2023-40581? CVE-2023-40581 is a high-severity OS command injection vulnerability in yt-dlp (pip), affecting versions >= 2021.04.11, < 2023.09.24. It is fixed in 2023.09.24. Untrusted input reaches a shell command, allowing arbitrary commands to run on the host.
2. How severe is CVE-2023-40581? CVE-2023-40581 has a CVSS score of 8.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of yt-dlp are affected by CVE-2023-40581? yt-dlp (pip) versions >= 2021.04.11, < 2023.09.24 is affected.
4. Is there a fix for CVE-2023-40581? Yes. CVE-2023-40581 is fixed in 2023.09.24. Upgrade to this version or later.
5. Is CVE-2023-40581 exploitable, and should I be worried? Whether CVE-2023-40581 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2023-40581 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2023-40581? Upgrade yt-dlp to 2023.09.24 or later.