nanoid: custom generators can loop indefinitely when size is zero
nanoid (Nano ID) before 5.1.6 contains an infinite loop in the customAlphabet and customRandom functions. When these functions are configured with a size of 0, the internal generation loop never satisfies its exit condition and spins indefinitely, hanging the calling thread. An application that passes an unvalidated, attacker-controlled size of 0 to these functions is exposed to a denial-of-service condition.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | nanoid | < 3.3.18, >= 4.0.0, < 5.1.6 | 3.3.18, 5.1.6 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-67213
- https://github.com/ai/nanoid/commit/cb3626d0f3342fdf179cd425fd9c4fbb92c7d0e7
- https://github.com/ai/nanoid/commit/e10f8d40ce9d1ab47f66d65a16b48086432730d0
- https://github.com/ai/nanoid/commit/f9d13f150847d117877adee3460a46eceb0cf49b
- https://github.com/ai/nanoid
- https://github.com/ai/nanoid/releases/tag/3.3.17
- https://github.com/ai/nanoid/releases/tag/3.3.18
- https://github.com/ai/nanoid/releases/tag/5.1.6
- https://www.vulncheck.com/advisories/nanoid-before-infinite-loop-via-zero-size-in-customalphabet-and-customrandom
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H- Weakness (CWE)
CWE-835- Platform
- npm
- Package
nanoid- Disclosed
- 29.07.2026
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2v37-7h3g-55p8 - CC BY 4.0
Vulnerability history: nanoid
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 01.2022 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 3
- Medium 2
Disclosures per year
- 2022: 1
- 2023: 0
- 2024: 1
- 2025: 0
- 2026: 3
-
nanoid: custom generators can loop indefinitely when size is zero this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.