How severe is GHSA-42h4-v29r-42qg?

GHSA-42h4-v29r-42qg has a CVSS score of 8.3/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-42h4-v29r-42qg?

GHSA-42h4-v29r-42qg affects the following packages: yt-dlp (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-42h4-v29r-42qg?

Update yt-dlp to 2023.09.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-42h4-v29r-42qg is resolved across your whole dependency graph.

How do I detect GHSA-42h4-v29r-42qg in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yt-dlp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-42h4-v29r-42qg if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-42h4-v29r-42qg?

O3 pinpoints whether GHSA-42h4-v29r-42qg is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-42h4-v29r-42qg actively exploited in the wild?

Yes. There are 1 known exploit references for GHSA-42h4-v29r-42qg, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for GHSA-42h4-v29r-42qg?

GHSA-42h4-v29r-42qg has an EPSS (Exploit Prediction Scoring System) score of 1.3%, placing it in the 67th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-42h4-v29r-42qg?

GHSA-42h4-v29r-42qg is classified as OS Command Injection (CWE-78). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was GHSA-42h4-v29r-42qg published, and has it been updated?

GHSA-42h4-v29r-42qg was published on September 25, 2023 and was last updated on February 4, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-42h4-v29r-42qg

HIGH

yt-dlp on Windows vulnerable to `--exec` command injection when using `%q`

Also known asCVE-2023-40581

Published

Sep 25, 2023

Updated

Feb 4, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

1.3%probability of exploitation in next 30 days

Lower Risk67th percentile-11.69%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐍yt-dlp

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`yt-dlp`	≥ 2021.04.11&&< 2023.09.24	2023.09.24

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

yt-dlp is a youtube-dl fork with additional features and fixes. yt-dlp a…

github.comNVDSep 2023

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yt-dlp. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update yt-dlp to 2023.09.24 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-42h4-v29r-42qg is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-42h4-v29r-42qg is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-42h4-v29r-42qg. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact [`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. However, the escaping used for `cmd` (the shell used by Python's `subprocess` on Windows) did not properly escape special characters, which

O3 Security · Impact-Aware SCA

Is GHSA-42h4-v29r-42qg in your dependencies?

O3 detects GHSA-42h4-v29r-42qg across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

GHSA-42h4-v29r-42qg

EPSS Exploitation Probability

Blast Radius

Description

Impact

Patches

Workarounds

References

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

How O3 protects you

Frequently Asked Questions

Is GHSA-42h4-v29r-42qg in your dependencies?