CVE-2026-119051
flat through 6.0.1 contains an uncontrolled resource allocation vulnerability in unflatten() that…
- Risk score
- 40/100
- CVSS
- 5.9 v3.1
- Exploit chance (30 days)
- 0.3%
- Published
- 29 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 5.9 medium
References
- https://github.com/hughsk/flat
- https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L137-L142
- https://github.com/hughsk/flat/blob/1d68e1d06c0210cff31e5c61ac177f3e2d3fa564/index.js#L65-L75
- https://github.com/hughsk/flat/issues/195
- https://www.vulncheck.com/advisories/flat-through-6.0.1-denial-of-service-via-unflatten-numeric-array-index-keys
Original 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.
Last activity 29 Oct 2026. Patch Forecast updates every hour.