PYSEC-2026-2064

Vulnerability from pysec - Published: 2026-07-07 11:45 - Updated: 2026-07-07 17:25
VLAI
Details

Impact

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

Patches

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.

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
Severity
8.3 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
Impacted products
Name purl
yt-dlp pkg:pypi/yt-dlp
Aliases
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "yt-dlp",
        "purl": "pkg:pypi/yt-dlp"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2021.04.11"
            },
            {
              "fixed": "2023.09.24"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2021.10.10",
        "2021.10.22",
        "2021.10.9",
        "2021.11.10",
        "2021.11.10.1",
        "2021.12.1",
        "2021.12.25",
        "2021.12.27",
        "2021.4.11",
        "2021.4.22",
        "2021.5.11",
        "2021.5.20",
        "2021.6.1",
        "2021.6.23",
        "2021.6.8",
        "2021.6.9",
        "2021.7.21",
        "2021.7.24",
        "2021.7.7",
        "2021.8.10",
        "2021.8.2",
        "2021.9.1",
        "2021.9.2",
        "2021.9.25",
        "2022.1.21",
        "2022.10.4",
        "2022.11.11",
        "2022.2.3",
        "2022.2.4",
        "2022.3.8",
        "2022.3.8.1",
        "2022.3.8.2",
        "2022.4.8",
        "2022.5.18",
        "2022.6.22",
        "2022.6.22.1",
        "2022.6.29",
        "2022.7.17",
        "2022.7.18",
        "2022.8.14",
        "2022.8.19",
        "2022.8.8",
        "2022.9.1",
        "2023.1.2",
        "2023.1.6",
        "2023.2.17",
        "2023.3.3",
        "2023.3.4",
        "2023.6.21",
        "2023.6.22",
        "2023.7.6"
      ]
    }
  ],
  "aliases": [
    "CVE-2023-40581",
    "GHSA-42h4-v29r-42qg"
  ],
  "details": "### Impact\n[`yt-dlp`](https://github.com/yt-dlp/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.\n\nHowever, the escaping used for `cmd` (the shell used by Python\u0027s `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`.\n\nSupport for output template expansion in `--exec`, along with this vulnerable behavior, was added to `yt-dlp` in version [2021.04.11](https://github.com/yt-dlp/yt-dlp/releases/tag/2021.04.11).\n\n```shell\n\u003e yt-dlp https://youtu.be/Jo66yyCpHcQ --exec \"echo %(title)q\"\n[youtube] Extracting URL: https://youtu.be/Jo66yyCpHcQ\n[youtube] Jo66yyCpHcQ: Downloading webpage\n[youtube] Jo66yyCpHcQ: Downloading ios player API JSON\n[youtube] Jo66yyCpHcQ: Downloading android player API JSON\n[youtube] Jo66yyCpHcQ: Downloading m3u8 information\n[info] Jo66yyCpHcQ: Downloading 1 format(s): 135+251\n[download] Destination: \uff02\u0026echo(\u0026echo(pwned\u0026rem( [Jo66yyCpHcQ].f135.mp4\n[download] 100% of    4.85KiB in 00:00:00 at 60.20KiB/s\n[download] Destination: \uff02\u0026echo(\u0026echo(pwned\u0026rem( [Jo66yyCpHcQ].f251.webm\n[download] 100% of    4.80KiB in 00:00:00 at 31.58KiB/s\n[Merger] Merging formats into \"\uff02\u0026echo(\u0026echo(pwned\u0026rem( [Jo66yyCpHcQ].mkv\"\nDeleting original file \uff02\u0026echo(\u0026echo(pwned\u0026rem( [Jo66yyCpHcQ].f135.mp4 (pass -k to keep)\nDeleting original file \uff02\u0026echo(\u0026echo(pwned\u0026rem( [Jo66yyCpHcQ].f251.webm (pass -k to keep)\n[Exec] Executing command: echo \"\\\"\u0026echo(\u0026echo(pwned\u0026rem(\"\n\"\\\"\n\npwned\n```\n\n### Patches\nyt-dlp version 2023.09.24 fixes this issue by properly escaping each special character.\n`\\n` will be replaced by `\\r`, as no way of escaping it has been found.\n\n### Workarounds\nIt 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.\n\nFor Windows users who are not able to upgrade:\n- Avoid using any output template expansion in `--exec` other than `{}` (filepath).\n- If expansion in `--exec` is needed, verify the fields you are using do not contain `\"`, `|` or `\u0026`.\n- Instead of using `--exec`, write the info json and load the fields from it instead.\n\n### References\n- https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-42h4-v29r-42qg\n- https://nvd.nist.gov/vuln/detail/CVE-2023-40581\n- https://github.com/yt-dlp/yt-dlp/releases/tag/2023.09.24\n- https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.09.24.003044\n- https://github.com/yt-dlp/yt-dlp/commit/de015e930747165dbb8fcd360f8775fd973b7d6e",
  "id": "PYSEC-2026-2064",
  "modified": "2026-07-07T17:25:52.678461Z",
  "published": "2026-07-07T11:45:25.140715Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/yt-dlp/yt-dlp/security/advisories/GHSA-42h4-v29r-42qg"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2023-40581"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yt-dlp/yt-dlp/commit/de015e930747165dbb8fcd360f8775fd973b7d6e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/yt-dlp/yt-dlp"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.09.24.003044"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yt-dlp/yt-dlp/releases/tag/2021.04.11"
    },
    {
      "type": "WEB",
      "url": "https://github.com/yt-dlp/yt-dlp/releases/tag/2023.09.24"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/yt-dlp"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-42h4-v29r-42qg"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": " yt-dlp on Windows vulnerable to `--exec` command injection when using `%q`"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.