CVE-2026-26331 is a high-severity (CVSS 8.8) OS Command Injection vulnerability in yt-dlp. A fix is available for yt-dlp — see the affected versions and patch details below.
yt-dlp: Arbitrary Command Injection when using the `--netrc-cmd` option
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-26331.
EPSS Exploitation Probability
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.
How urgent is this, really
CVE-2026-26331 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
yt-dlpReal-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
Summary
When yt-dlp's --netrc-cmd command-line option (or netrc_cmd Python API parameter) is used, an attacker could achieve arbitrary command injection on the user's system with a maliciously crafted URL.
Impact
yt-dlp maintainers assume the impact of this vulnerability to be high for anyone who uses --netrc-cmd in their command/configuration or netrc_cmd in their Python scripts. Even though the maliciously crafted URL itself will look very suspicious to many users, it would be trivial for a maliciously crafted webpage with an inconspicuous URL to covertly exploit this vulnerability via HTTP redirect. Users without --netrc-cmd in their arguments or netrc_cmd in their scripts are unaffected. No evidence has been found of this exploit being used in the wild.
Patches
yt-dlp version 2026.02.21 fixes this issue by validating all netrc "machine" values and raising an error upon unexpected input.
Workarounds
It is recommended to upgrade yt-dlp to version 2026.02.21 as soon as possible.
Users who are unable to upgrade should avoid using the --netrc-cmd command-line option (or netrc_cmd Python API parameter), or they should at least not pass a placeholder ({}) in their --netrc-cmd argument.
Details
yt-dlp's --netrc-cmd option can be used to run any arbitrary shell command to retrieve site login credentials so that the user doesn't have to store the credentials as plaintext in the filesystem. The --netrc-cmd argument is a shell command with an optional placeholder ({}). If the placeholder is present in the argument, it is replaced with the netrc "machine" value, which specifies the site for which login credentials are needed.
The netrc "machine" value is usually explicitly defined in yt-dlp's extractor code for a given site. However, yt-dlp has four extractors where the netrc "machine" value needs to be dynamically sourced from the site's hostname. And in three of those extractors (GetCourseRuIE, TeachableIE and TeachableCourseIE), wildcard matches are allowed for one or more subdomains of the hostname. This can result in a netrc "machine" value that contains special shell characters.
The --netrc-cmd argument is executed by a modified version of Python's subprocess.Popen with shell=True, which means that any special characters may be interpreted by the host shell, potentially leading to arbitrary command injection.
Here is an example of maliciously crafted URL input that exploits the vulnerability:
> yt-dlp --netrc-cmd "echo {}" "https://;echo pwned>&2;#.getcourse.ru/video"
[GetCourseRu] Executing command: echo getcourseru
WARNING: [GetCourseRu] Failed to parse .netrc: bad toplevel token 'getcourseru' (-, line 2)
[GetCourseRu] Extracting URL: https://;echo pwned>&2;#.getcourse.ru/video
[GetCourseRu] Executing command: echo ;echo pwned>&2;
pwned
[GetCourseRu] No authenticators for ;echo pwned>&2;
[GetCourseRu] video: Downloading webpage
Although only 3 of yt-dlp's extractors are directly susceptible to this attack, yt-dlp's "generic" extractor will follow HTTP redirects and try to match the resulting URL with one of the dedicated extractors. This means that any URL processed by the generic extractor could ultimately lead to a maliciously crafted URL that is matched by one of the vulnerable extractors. Hypothetically, an attacker could create a website with an inconspicuous URL and legitimate-looking media content that would serve an HTTP redirect to a maliciously crafted URL when it detects a request from yt-dlp.
References
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | yt-dlp | ≥ 2023.06.21&&< 2026.02.21 | 2026.02.21pip install --upgrade 'yt-dlp==2026.02.21' |
Detection & mitigation playbook
Open-source dependencyDetect
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 2026.02.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-26331 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-26331 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-26331. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-26331 in your dependencies?
O3 Security finds CVE-2026-26331 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.