How severe is CVE-2026-31808?

CVE-2026-31808 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-31808?

CVE-2026-31808 affects the following packages: file-type (npm). Ecosystems affected: npm.

How do I fix CVE-2026-31808?

Update file-type to 21.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31808 is resolved across your whole dependency graph.

How do I detect CVE-2026-31808 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for file-type, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-31808 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-31808 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-31808 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-31808?

CVE-2026-31808 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 31th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-31808?

CVE-2026-31808 is classified as CWE-835 (CWE-835). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-31808 published, and has it been updated?

CVE-2026-31808 was published on March 10, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦

📦 npm

Not in CISA KEV

MEDIUM severity

CVE-2026-31808 — file-type

MEDIUMFix: sindresorhus/file-type@319abf8

CVE-2026-31808 is a medium-severity (CVSS 5.3) CWE-835 vulnerability in file-type. A fix is available for file-type — see the affected versions and patch details below.

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

Also known asGHSA-5v7r-6r5c-r473

Published

Mar 10, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-31808.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk+0.02%

Lower risk than most CVEs31th percentile — riskier than 31% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

4Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream

file-typenpm

79.6Mdownloads / week

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]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`file-type`	≥ 13.0.0&&< 21.3.1	21.3.1`npm install file-type@21.3.1`

Affected Products

1 product · 1 configurations

Application

file-typesindresorhus

≥ 13.0.0 && < 21.3.1

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for file-type, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update file-type to 21.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31808 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Source: Red Hat security advisory for CVE-2026-31808 (CC BY 4.0)

Frequently Asked Questions

### 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.