CVE-2026-55091

flat-to-nested (NPM, versions ≥1.1.0, ≤1.1.1) is vulnerable to prototype pollution (CWE-1321) in FlatToNested.prototype.convert (index.js). The function uses attacker-controlled id and parent field values directly as keys in plain objects, so a value of "__proto__" resolves via the prototype chai...

CVE-2026-55091: Improperly Controlled Modification of Dynamically-Determined Object Attributes

flat-to-nested converts a hierarchy from a flat representation to a nested representation. Prior to 1.1.2, FlatToNested.prototype.convert in index.js uses attacker-influenced id and parent record fields directly as keys in the plain temp and pendingChildOf objects. When parent or id is proto,...