CVE-2026-73086

High

Description

nanoid is a secure, URL-friendly, unique string ID generator for JavaScript. Prior to versions 3.3.12 and 5.1.11, the nanoid(size) function in index.js and index.cjs coerces the user-influenced size parameter to a signed 32-bit integer, allowing a value of 2147483648 to become -2147483648 and corrupt the process-wide CSPRNG poolOffset in fillPool(), which causes subsequent session tokens, CSRF tokens, API keys, and unique identifiers to become the deterministic string "uuuuuuuuuuuuuuuuuuuuu" until the process restarts. This issue is fixed in versions 3.3.12 and 5.1.11.

SeverityHigh

CVSS7.4

Exploit probability—

ProductNanoid

PublishedAug 11, 2026

First seenAug 11, 2026

Weakness typeCWE-190Integer overflow

How to fix

Update

nanoid3.3.12, 5.1.11 or later

Affected products

Product	Affected versions	Fixed in
nanoidnpm	v < 3.3.12, 4.0.0 ≤ v < 5.1.11	3.3.12, 5.1.11

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