yt‑dlp is a command‑line audio/video downloader. Prior to 2026.06.09, if aria2c is used as an external downloader for a fragmented manifest format, such as an HLS/DASH stream, yt‑dlp passes insufficiently sanitized input to aria2c that allows an attacker to perform an arbitrary file write. On Windows platforms, this can lead to immediate arbitrary code execution. On non‑Windows platforms, this can lead to arbitrary code execution upon the next invocation of yt‑dlp. This vulnerability is fixed in 2026.06.09.

The vulnerability impacts all users of yt‑dlp versions earlier than 2026.06.09 on both Windows and non‑Windows platforms. Windows users can experience immediate code execution, whereas non‑Windows users can achieve code execution on the next execution of yt‑dlp.

The CVSS score of 8.3 reflects a high severity. Although no EPSS score is available, the system‑wide impact and absence of a mitigated alternative mean exploitation is not theoretically improbable. The vulnerability is not listed in KEV. The likely attack vector involves an attacker providing a malicious fragmented manifest (or URL containing a crafted path) to yt‑dlp when aria2c is used as the external downloader. Once the file write is performed, a hostile executable can be placed in a location that yt‑dlp or the underlying operating system will subsequently load or launch, achieving code execution with the privileges of the yt‑dlp process.