CVE-2025-71403: better-auth before 1.1.20 Open Redirect via trustedOrigins Bypass

Severity: high (CVSS 7.1 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: 2026-08-01 · updated 2026-10-06
Weakness: CWE-601

Description

better-auth versions before 1.1.20 contain a bypass vulnerability in trustedOrigins validation logic affecting absolute URLs and wildcard domains. Attackers can construct malicious callbackURL parameters that pass origin checks and trigger open redirects to steal sensitive tokens for account takeover.

Affected products

better-auth: before 1.1.20 — fixed in 1.1.20

How to fix

Upgrade to a fixed version: better-auth 1.1.20. Check the vendor advisory for mitigations.

References

https://github.com/better-auth/better-auth/security/advisories/GHSA-vp58-j275-797x
https://www.vulncheck.com/advisories/better-auth-before-open-redirect-via-trustedorigins-bypass

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