8.3 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:H
0.005 Low
EPSS
Percentile
77.1%
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
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.
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:
--exec
other than {}
(filepath).--exec
is needed, verify the fields you are using do not contain "
, |
or &
.--exec
, write the info json and load the fields from it instead.CPE | Name | Operator | Version |
---|---|---|---|
yt-dlp | ge | 2021.04.11 | |
yt-dlp | lt | 2023.09.24 |
github.com/advisories/GHSA-42h4-v29r-42qg
github.com/yt-dlp/yt-dlp-nightly-builds/releases/tag/2023.09.24.003044
github.com/yt-dlp/yt-dlp/commit/de015e930747165dbb8fcd360f8775fd973b7d6e
github.com/yt-dlp/yt-dlp/releases/tag/2021.04.11
github.com/yt-dlp/yt-dlp/releases/tag/2023.09.24
github.com/yt-dlp/yt-dlp/security/advisories/GHSA-42h4-v29r-42qg
nvd.nist.gov/vuln/detail/CVE-2023-40581