file-type affected by infinite loop in ASF parser on malformed input with zero-size sub-header

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file-type detects the file type of a file, stream, or data. Prior to 21.3.1, a denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a size field of zero, the parser enters an infinite loop. The payload value becomes negative (-24), causing tokenizer.ignore(payload) to move the read position backwards, so the same sub-header is read repeatedly forever. Any application that uses file-type to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload. Fixed in version 21.3.1.

Source published

10 Mar 2026 21:01:55 UTC

Source modified

11 Mar 2026 16:00:14 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

file-type detects the file type of a file, stream, or data. Prior to 21.3.1, a denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a size field of zero, the parser enters an infinite loop. The payload value becomes negative (-24), causing tokenizer.ignore(payload) to move the read position backwards, so the same sub-header is read repeatedly forever. Any application that uses file-type to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload. Fixed in version 21.3.1.

Source published

Mar 10, 2026, 9:01:55 PM (timezone not stated)

Source modified

Mar 11, 2026, 4:00:14 PM (timezone not stated)

Saved here

15 Nov 2026 09:31:53 UTC

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EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

file-type detects the file type of a file, stream, or data. Prior to 21.3.1, a denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a size field of zero, the parser enters an infinite loop. The payload value becomes negative (-24), causing tokenizer.ignore(payload) to move the read position backwards, so the same sub-header is read repeatedly forever. Any application that uses file-type to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload. Fixed in version 21.3.1.

Source published

10 Mar 2026 21:16:50 UTC

Source modified

17 Jun 2026 10:34:30 UTC

Saved here

25 Oct 2026 07:19:14 UTC

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CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

### Impact A denial of service vulnerability exists in the ASF (WMV/WMA) file type detection parser. When parsing a crafted input where an ASF sub-header has a `size` field of zero, the parser enters an infinite loop. The `payload` value becomes negative (-24), causing `tokenizer.ignore(payload)` to move the read position backwards, so the same sub-header is read repeatedly forever. Any application that uses `file-type` to detect the type of untrusted/attacker-controlled input is affected. An attacker can stall the Node.js event loop with a 55-byte payload. ### Patches Fixed in version 21.3.1. Users should upgrade to >= 21.3.1. ### Workarounds Validate or limit the size of input buffers before passing them to `file-type`, or run file type detection in a worker thread with a timeout. ### References - Fix commit: 319abf871b50ba2fa221b4a7050059f1ae096f4f ### Reporter [email protected]

Source published

10 Mar 2026 23:57:09 UTC

Source modified

10 Sep 2026 03:50:37 UTC

Saved here

24 Oct 2026 13:17:17 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Publisher rating · MODERATE