Vulnerability in Sindresorhus File-Type
CVE-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. 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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (33.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 33.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Sindresorhus File-Type — versions >= 13.0.0, < 21.3.1
Weakness classification (CWE)
References
- github.com/sindresorhus/file-type/security/advisories/GHSA-5v7r-6r5c-r473 (Patch, Mitigation, Vendor Advisory)
- github.com/sindresorhus/file-type/commit/319abf871b50ba2fa221b4a7050059f1ae096f… (Patch)
Frequently asked questions
- What is CVE-2026-31808?
- CVE-2026-31808 is a medium-severity vulnerability in Sindresorhus File-Type, classified under Loop with Unreachable Exit Condition (Infinite Loop). CVSS score: 5.3/10. Published 2026-03-10.
- How severe is CVE-2026-31808?
- Medium severity. CVSS v3 base score is 5.3 out of 10.