CVE-2026-31808: sindresorhus file-type Infinite Loop

Vulnerability summary

CVE-2026-31808 is a medium (CVSS 5.3) Infinite Loop vulnerability in sindresorhus file-type. EPSS estimates a 0.43% chance of exploitation in the next 30 days, higher than 36.6% of scored vulnerabilities.

Timeline

1. 10-03-2026
   PublishedVulnerability first disclosed.
2. 11-03-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.