What’s Vulnerable › Vulnerabilities

CVE-2026-73086: nanoid: Integer Overflow or Wraparound

• Severity: high (CVSS 7.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-11 · updated 2026-10-24
• Weakness: CWE-190

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.

Affected products

• ai nanoid: before 3.3.12; from 4.0.0, < 5.1.11

References

• https://github.com/ai/nanoid/commit/7087969281cab8ba8ae3babf1894e819068b3bb4
• https://github.com/ai/nanoid/commit/821dfed7b5db7f88e92f56c60eef32c8135077c3
• https://github.com/ai/nanoid/commit/b0036ed60dc9facd7f1191a50dfb3076500202ac
• https://github.com/ai/nanoid/releases/tag/3.3.12
• https://github.com/ai/nanoid/releases/tag/5.1.11
• https://github.com/ai/nanoid/security/advisories/GHSA-xwg4-73v4-xw9w

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