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Medium

Better Auth URL parameter HTML Injection (Reflected Cross-Site scripting)

  • Disclosed: 05.02.2025
  • Updated: 11.10.2026 10:22

Summary

The better-auth /api/auth/error page was vulnerable to HTML injection, resulting in a reflected cross-site scripting (XSS) vulnerability.

Details

The value of error URL parameter was reflected as HTML on the error page: https://github.com/better-auth/better-auth/blob/05ada0b79dbcac93cc04ceb79b23ca598d07830c/packages/better-auth/src/api/routes/error.ts#L81

Impact

An attacker who exploited this vulnerability by coercing a user to visit a specially-crafted URL could execute arbitrary JavaScript in the context of the user's browser.

Affected software

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PlatformPackageVulnerable versionsFixed in
npm package better-auth >= 0.0.2, < 1.1.16 1.1.16

References

CVSS score -
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness (CWE)
CWE-79
Platform
npm
Package
better-auth
Disclosed
05.02.2025
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-9x4v-xfq5-m8x5 - CC BY 4.0

Vulnerability history: better-auth

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (22) in the archive
Total entries
22
First → latest
12.2024 07.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • High 14
  • Medium 3
  • Low 3

Disclosures per year

Severity:
  1. Better Auth: Account takeover via pre-account hijacking on magic-link and email-OTP sign-in
    High · 8.3 CVE-2026-67327 >= 1.1.3, < 1.6.22, >= 1.7.0-beta.0, < 1.7.0-beta.10 1.6.22, 1.7.0-beta.10
  2. @better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive
    High · 8.1 CVE-2026-53518 < 1.6.11 1.6.11
  3. Better Auth: OAuth refresh-token rotation forks the token family on concurrent redemption
    High · 8.1 CVE-2026-53517 >= 1.4.8-beta.7, < 1.6.0 1.6.0
  4. Better Auth has insecure cryptographic defaults in oidcProvider: alg=none advertised and plain PKCE accepted by default
    High · 8.7 CVE-2026-67336 < 1.6.11 1.6.11
  5. Better Auth has stored XSS in the auth-server origin via javascript: redirect_uri in oidc-provider and mcp
    High · 7.7 CVE-2026-67333 < 1.6.13, >= 1.7.0-beta.0, < 1.7.0-beta.4 1.6.13, 1.7.0-beta.4
  6. Better Auth has an account takeover issue via OAuth auto-link to unverified pre-registered email
    High · 8.3 CVE-2026-53516 < 1.6.11 1.6.11
  7. Better Auth vulnerable to unauthorized invitation acceptance via unverified email match in organization plugin
    High · 7.7 CVE-2026-53514 < 1.6.11 1.6.11
  8. Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins
    Critical · 9.1 CVE-2026-53512 < 1.6.11 1.6.11
  9. Better Auth: Device authorization approve and deny accept any authenticated session while the user code is pending
    High · 7.6 CVE-2026-45337 >= 1.6.0, < 1.6.11 1.6.11
  10. Better Auth: Rate limiter keys IPv6 addresses individually and is bypassable via prefix rotation
    High · 7.3 CVE-2026-45364 < 1.4.17, >= 1.5.0-beta.1, < 1.5.0-beta.9 1.4.17, 1.5.0-beta.9
  11. Better Auth Has Two-Factor Authentication Bypass via Premature Session Caching (session.cookieCache)
    Critical CVE-2026-67337 < 1.4.9 1.4.9
  12. Better Auth's rou3 Dependency has Double-Slash Path Normalization which can Bypass disabledPaths Config and Rate Limits
    High · 8.6 CVE-2025-71399 < 1.4.5 1.4.5
  13. Better Auth affected by external request basePath modification DoS
    High CVE-2025-71401 < 1.4.2 1.4.2
  14. Better Auth: Unauthenticated API key creation through api-key plugin
    High · 8.6 CVE-2025-61928 < 1.3.26 1.3.26
  15. Better Auth allows bypassing the trustedOrigins Protection which leads to ATO
    High · 7.1 CVE-2025-71403 < 1.1.21 1.1.21
  16. Better Auth URL parameter HTML Injection (Reflected Cross-Site scripting) this entry
    Medium CVE-2025-71404 >= 0.0.2, < 1.1.16 1.1.16
  17. Better Auth has an Open Redirect Vulnerability in Verify Email Endpoint
    High CVE-2024-56734 < 1.1.6 1.1.6

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