---
id: CVE-2026-67214
title: >-
  nanoid (Nano ID) before 3.3.16 and 5.1.16 contains an infinite loop in the
  customAlphabet and nanoid functions of its non-secure module
  (nanoid/non-secure)
summary: >-
  nanoid (Nano ID) before 3.3.16 and 5.1.16 contains an infinite loop in the
  customAlphabet and nanoid functions of its non-secure module
  (nanoid/non-secure). When these functions are given a negative size, the loop
  counter is decremented …
severity: medium
cvss: 5.9
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-835
vendor: nanoid_project
product: nanoid
affected:
  - nanoid < 3.3.16
  - 'nanoid >= 4.0.0, < 5.1.16'
patched:
  - nanoid 5.1.16
published: '2026-07-29'
updated: '2026-09-30'
sourceUpdated: '2026-09-30T16:54:12.183'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-67214'
references:
  - url: >-
      https://github.com/ai/nanoid/commit/6ccc67bbaba71d3d77a21d9b636f4171a268ce49
    label: disclosure@vulncheck.com
  - url: 'https://github.com/ai/nanoid/releases/tag/3.3.16'
    label: disclosure@vulncheck.com
  - url: 'https://github.com/ai/nanoid/releases/tag/5.1.16'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nanoid-before-infinite-loop-via-negative-size-in-non-secure-module
    label: disclosure@vulncheck.com
tags:
  - nvd
epss: 0.0033
epssPercentile: 0.23675
ingestedAt: '2026-09-30T17:13:20.782Z'
---

## Overview

nanoid (Nano ID) before 3.3.16 and 5.1.16 contains an infinite loop in the customAlphabet and nanoid functions of its non-secure module (nanoid/non-secure). When these functions are given a negative size, the loop counter is decremented from a negative value and never reaches its termination condition, spinning indefinitely and hanging the calling thread. An application that passes an unvalidated, attacker-controlled negative size to these functions is exposed to a denial-of-service condition.

## Affected

- `nanoid < 3.3.16`
- `nanoid >= 4.0.0, < 5.1.16`

## Remediation

Upgrade past the affected range:

- `nanoid 5.1.16`