{"id":"CVE-2026-119051","state":"PUBLISHED","title":"flat through 6.0.1 Denial of Service via unflatten() Numeric Array Index Keys","description":"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.","publishedAt":"2026-10-29T13:08:52.215Z","updatedAt":"2026-10-29T13:08:52.215Z","severity":{"score":8.2,"label":"High","version":"4.0","vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","source":"VulnCheck"},"assigner":"VulnCheck","products":["hughsk flat"],"affected":[{"vendor":"hughsk","product":"flat","packageURL":"pkg:npm/flat","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"6.0.1","versionType":"custom"}],"repo":"https://github.com/hughsk/flat"}],"references":["https://github.com/hughsk/flat/issues/195","https://github.com/hughsk/flat","https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L65-L75","https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L137-L142","https://www.vulncheck.com/advisories/flat-through-6.0.1-denial-of-service-via-unflatten-numeric-array-index-keys"],"weaknesses":["CWE-770"],"ingestedAt":"2026-10-29T20:10:52.580Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/119xxx/CVE-2026-119051.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-119051","state":"PUBLISHED","datePublished":"2026-10-29T13:08:52.215Z","dateUpdated":"2026-10-29T13:08:52.215Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-10-29T11:51:51.276Z"},"containers":{"cna":{"title":"flat through 6.0.1 Denial of Service via unflatten() Numeric Array Index Keys","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"hughsk","product":"flat","packageURL":"pkg:npm/flat","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"6.0.1","versionType":"custom"}],"repo":"https://github.com/hughsk/flat"}],"references":[{"url":"https://github.com/hughsk/flat/issues/195","tags":["issue-tracking"],"name":"GitHub Issue #195"},{"url":"https://github.com/hughsk/flat","tags":["product"]},{"url":"https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L65-L75","tags":["technical-description"]},{"url":"https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L137-L142","tags":["technical-description"]},{"url":"https://www.vulncheck.com/advisories/flat-through-6.0.1-denial-of-service-via-unflatten-numeric-array-index-keys","name":"VulnCheck Advisory: flat through 6.0.1 Denial of Service via unflatten() Numeric Array Index Keys","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","cvssV4_0":{"version":"4.0","vectorString":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","attackVector":"NETWORK","attackComplexity":"HIGH","attackRequirements":"PRESENT","privilegesRequired":"NONE","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE","vulnAvailabilityImpact":"HIGH","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","subAvailabilityImpact":"NONE","baseScore":8.2,"baseSeverity":"HIGH"}},{"format":"CVSS","cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","attackVector":"NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseScore":5.9,"baseSeverity":"MEDIUM"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-10-29T13:08:52.215Z"},"datePublic":"2026-09-16T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:flat_project:flat:*:*:*:*:*:*:*:*","versionEndIncluding":"6.0.1"}]}]}],"credits":[{"lang":"en","value":"Yu Bao, PayPal Cyber Security Team","type":"finder"}],"x_generator":{"engine":"vulncheck-endgame"}}}}}