Resource exhaustion in Hughsk Flat
CVE-2026-119051
flat through 6.0.1 contains an uncontrolled resource allocation vulnerability in unflatten() that allows attackers to create huge sparse arrays via unbounded numeric keys. Attackers can supply flattened keys such as a.4294967294, causing iteration with forEach, spread or JSON.stringify to block the Node.js event loop.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/hughsk/flat/issues/195 (issue-tracking)
- github.com/hughsk/flat (product)
- github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js (technical-description)
- github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js (technical-description)
- www.vulncheck.com/advisories/flat-through-6.0.1-denial-of-service-via-unflatten… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-119051?
- CVE-2026-119051 is a medium-severity vulnerability in Hughsk Flat, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.9/10. Published 2026-10-29.
- How severe is CVE-2026-119051?
- Medium severity. CVSS v3 base score is 5.9 out of 10.