CVE-2026-119051 PUBLISHED

flat through 6.0.1 Denial of Service via unflatten() Numeric Array Index Keys

Assigner: VulnCheck
Reserved: 29.10.2026 Published: 29.10.2026 Updated: 29.10.2026

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.

CVSS 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
CVSS Score: 8.2

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	None	Integrity	None
Attack Requirements	Present	Availability	High	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 5.9

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	hughsk
Product	flat
Versions	Default: unaffected affected from 0 to 6.0.1 (incl.)

CVE-2026-119051 PUBLISHED

flat through 6.0.1 Denial of Service via unflatten() Numeric Array Index Keys

Metrics

Product Status

Credits

References

Problem Types