CVE Catalog

CVE-2026-119051

MediumCVSS 5.9
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.32%

25th percentile - higher than 25% of all known CVEs

Summary

The flat library through version 6.0.1 contains an uncontrolled resource allocation vulnerability in unflatten() that allows attackers to create huge sparse arrays via unbounded numeric keys. Keys such as a.4294967294 can block the Node.js event loop during iteration with forEach, spread, or JSON.stringify.

Risk Assessment

Resource exhaustion and blocking of the Node.js event loop may occur, causing denial of service for the application. The risk affects services processing untrusted input with the vulnerable flat version.

Recommendation

Update the flat library to a version later than 6.0.1. Validate and limit the size and structure of input passed to unflatten().

Related vulnerabilities

Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS