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GHSA-3v33-3wmw-3785
No affected components available
Impact
yt-dlp's DouyuTV and DouyuShow extractors used a cdn.bootcdn.net URL as a fallback for fetching a component of the crypto-js JavaScript library. When the Douyu extractor is used, yt-dlp extracts this JavaScript code and attempts to execute it externally using PhantomJS. bootcdn.net is owned by the bad actor responsible for the Polyfill JS supply chain attack that has been ongoing since at least June 2023. While there is no evidence that PhantomJS has been targeted by or is vulnerable to any attacks carried out by the Polyfill JS actor, there is the possibility that malicious JavaScript code may have been downloaded/cached by yt-dlp or executed by PhantomJS.
In order for this potential vulnerability to be exploited by any hypothetical attack, all 3 of the following conditions must be met:
- The user has PhantomJS installed on their system.
- The user passes a
douyu.comordouyutv.comURL to yt-dlp as input, or passes a URL that redirects to one of these domains. cdnjs.cloudflare.comis unavailable or blocked at the time of extraction, necessitating the usage of thecdn.bootcdn.netfallback; or it had been unavailable during a previous run of the Douyu extractor and JavaScript code fromcdn.bootcdn.nethad been cached to disk.
Patches
yt-dlp version 2024.07.07 fixes this issue by removing the URL pointing to the malicious CDN and by invalidating any Douyu extractor cache data created by unpatched versions of yt-dlp.
Workarounds
It is recommended to upgrade yt-dlp to version 2024.07.07 as soon as possible.
For users not able to upgrade:
- Avoid using the Douyu extractors (
--ies default,-douyutv,-douyushow) - Uninstall (or do not install) PhantomJS
Acknowledgement
Thanks to @LeSuisse for reporting this promptly after bootcdn.net was discovered to be under control of the same bad actor behind the polyfill.io supply chain attack.
References
- https://github.com/yt-dlp/yt-dlp/commit/6075a029dba70a89675ae1250e7cdfd91f0eba41
- https://sansec.io/research/polyfill-supply-chain-attack
Measures severity based on intrinsic characteristics of the vulnerability, independent of environment.
No exploitation activity has been observed at this time. Continue routine monitoring.
Probability that this vulnerability will be exploited in the wild within the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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