CVE-2026-50574

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.

Details

When downloading a fragmented manifest format such as an HLS or DASH stream, yt-dlp first extracts a list of all fragment URLs from the stream's manifest. If the user has selected aria2c as an external downloader, yt-dlp then constructs an input file for aria2c from the fragment URL list and passes its filepath as the argument to aria2c's -i option.

aria2c's -i (or --input-file) option allows for downloading a list of URIs from the given text file. The text file must be formatted as a list of URIs separated by newlines. aria2c's format permits configuration lines for each URI, which can contain command-line options to be given to aria2c. These optional lines follow each URI line and are signified only by leading whitespace. yt-dlp constructs the input file with these optional lines so that it's able to specify the output filename for each fragment using the out= option.

yt-dlp's utilization of the aria2c input file format presents two known attack vectors:

1. An attacker can craft a malicious DASH manifest with one or more fragment URLs that contain 
, which is the HTML escape sequence for a newline. yt-dlp interprets this escape sequence as an actual newline character when writing the fragment URLs to the aria2c input file, which allows for an attacker to inject arbitrary aria2c options into the input file. With option injection, the attacker can achieve arbitrary file writes. This attack vector is possible only via downloads of DASH formats, since their manifests are an XML format which necessitates unescaping of HTML special characters.

2. An attacker can craft a malicious metadata response where the data parsed by yt-dlp as the title field (or any other metadata field that the user includes in their output template) contains strategically placed newlines and magnet URIs. If the user has passed the --no-windows-filename option to disable sanitization of newlines in output filenames, the attacker is able to achieve arbitrary file writes by injecting arbitrary URIs and options into the aria2c input file. This attack vector is possible via downloads of both HLS and DASH formats.

On Windows, attacker-controlled file writes can lead to immediate arbitrary code execution: the attacker could write a malicious executable file named ffmpeg.exe to the current working directory, and it could be invoked during the postprocessing stage if the user's yt-dlp.exe also resides in the current working directory.

On all platforms, attacker-controlled file writes can lead to arbitrary code execution on repeat invocations of yt-dlp: the attacker could write a yt-dlp configuration file (yt-dlp.conf) to the current working directory containing a malicious --exec argument.

Workarounds

It is recommended to upgrade yt-dlp to version 2026.06.09 as soon as possible.

For users who are not able to upgrade:

• Add --downloader dash,m3u8:native to your yt-dlp command.

CVE-2026-50574 has a CVSS score of 8.3 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2026.6.9); upgrading removes the vulnerable code path.

Kodem intelligence

yt-dlp version 2026.06.09 fixes this issue by removing support for downloading fragmented manifest formats with aria2c.

1. What is CVE-2026-50574? CVE-2026-50574 is a high-severity security vulnerability in yt-dlp (pip), affecting versions < 2026.6.9. It is fixed in 2026.6.9.
2. How severe is CVE-2026-50574? CVE-2026-50574 has a CVSS score of 8.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of yt-dlp are affected by CVE-2026-50574? yt-dlp (pip) versions < 2026.6.9 is affected.
4. Is there a fix for CVE-2026-50574? Yes. CVE-2026-50574 is fixed in 2026.6.9. Upgrade to this version or later.
5. Is CVE-2026-50574 exploitable, and should I be worried? Whether CVE-2026-50574 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-50574 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-50574? Upgrade yt-dlp to 2026.6.9 or later.