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

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: 2026-03-10 Last update: 2026-03-18 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-31808 is rated Low Risk (29.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.33%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-31808

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.03% 0.33% +0.30%
2 2026-03-21 0.06% 0.03% -0.03%
3 2026-03-16 — 0.06% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-31808

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]

Weakness enumeration for CVE-2026-31808

GitHub Security Advisory for CVE-2026-31808

GHSA-5v7r-6r5c-r473 · Severity: medium · Ecosystem: npm — file-type affected by infinite loop in ASF parser on malformed input with zero-size sub-header

OS Trackers for CVE-2026-31808

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2026-31808

Affected software / configurations for CVE-2026-31808

Vendor Product Version Raw CPE
sindresorhus file-type >= 13.0.0, < 21.3.1 cpe:2.3:a:sindresorhus:file-type:*:*:*:*:*:node.js:*:*

References for CVE-2026-31808

cvelogic Threat Intelligence