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Findings

CVE-2026-31808

file-type detects the file type of a file, stream, or data.

Published Mar 10, 2026 · updated Jun 17, 2026 · sindresorhus file-type

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.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 10, 2026 · NIST NVD

    Detected

    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 th

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 th

Affected

  • cpe sindresorhus/file-typeversion unspecified

Sources

  • CVE.orgVulnerability recordCVE-2026-31808

    Official CVE identifier

    cve.org
  • NIST NVDVulnerability recordCVE-2026-31808

    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

    nvd.nist.gov

References