file-type affected by infinite loop in ASF parser on malformed input with zero-size sub-header (CVE-2026-31808) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-31808GHSA-5V7R-6R5C-R473

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

Answer in brief

CVE-2026-31808 records a Medium severity (CVSS 5.3) vulnerability in file-type affected by infinite loop in ASF parser on malformed input with zero-size sub-header. The current sources do not mark it as known exploited. The current feed maps file-type (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 10, 2026Updated Sep 10, 2026Source checked Sep 10, 2026First seen by HOL Sep 10, 2026Material review Sep 10, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps file-type (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
file-typenpm	>=13.0.0 <21.3.1	21.3.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for file-type.
Review the reported fix. Update file-type to 21.3.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 10, 2026
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### 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]

Quoted source text, attributed separately from HOL analysis.