yt-dlp: Improper Neutralization of Special Elements used in an OS Command
CVE-2024-22423 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in yt-dlp, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected yt-dlp versions: >= 2021.04.11, < 2024.04.09. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.43% chance of exploitation within 30 days, higher than 73% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of yt-dlp you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.3 | High | CNA (github.com) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
yt-dlp is a youtube-dl fork with additional features and fixes. The patch that addressed CVE-2023-40581 attempted to prevent RCE when using `--exec` with `%q` by replacing double quotes with two double quotes. However, this escaping is not sufficient, and still allows expansion of environment variables. Support for output template expansion in `--exec`, along with this vulnerable behavior, was added to `yt-dlp` in version 2021.04.11. yt-dlp version 2024.04.09 fixes this issue by properly escaping `%`. It replaces them with `%%cd:~,%`, a variable that expands to nothing, leaving only the leading percent. It is recommended to upgrade yt-dlp to version 2024.04.09 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 `&`; and/or instead of using `--exec`, write the info json and load the fields from it instead.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an OS Command
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Patches and release notes
Third-party and government advisories
- kb.cert.org/vuls/id/123335Third Party Advisory
Other vulnerabilities in yt-dlp
- 8.8 High severity
- 9.6 Critical severity
- 9.6 Critical severity
- 7.4 High severity
- 8.8 High severity
- 8.1 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 10.0 Critical severity
- 8.8 High severity
- 8.8 High severity
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
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