Read the docs
TI-2025-20000 Aliases CVE-2025-27143GHSA-hjpm-7mrm-26w8

Beter Auth has an Open Redirect via Scheme-Less Callback Parameter

Priority HIGH 70CWE-601Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Spoofing
Confidentiality · integrity · availability
None · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-601.

Summary

Better Auth is an authentication and authorization library for TypeScript. Prior to version 1.1.21, the application is vulnerable to an open redirect due to improper validation of the callbackURL parameter in the email verification endpoint and any other endpoint that accepts callback url. While the server blocks fully qualified URLs, it incorrectly allows scheme-less URLs. This results in the browser interpreting the URL as a fully qualified URL, leading to unintended redirection. An attacker can exploit this flaw by crafting a malicious verification link and tricking users into clicking it. Upon successful email verification, the user will be automatically redirected to the attacker's website, which can be used for phishing, malware distribution, or stealing sensitive authentication tokens. This CVE is a bypass of the fix for GHSA-8jhw-6pjj-8723/CVE-2024-56734. Version 1.1.21 contains an updated patch.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0035 28th percentileScored 2026-11-07
Fix Fixed better-auth (better-auth): 1.1.20better-auth (npm): 1.1.20

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
better-authbetter-authbefore 1.1.201.1.20Patch availableCNA
—better-auth (npm)before 1.1.201.1.20Patch availableGHSA-hjpm-7mrm-26w8
  • better-auth Vendorbetter-auth Affected before 1.1.20 Fixed in 1.1.20 Patch available CNA
  • better-auth (npm) Vendor— Affected before 1.1.20 Fixed in 1.1.20 Patch available GHSA-hjpm-7mrm-26w8

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:*before 1.1.21Vulnerablebetter-auth
  • cpe:2.3:a:better-auth:better_auth:*:*:*:*:*:node.js:*:* Versions before 1.1.21 Vulnerable ·better-auth

Remediation

  • Fix · CNA better-auth (better-auth) Fixed in 1.1.20
  • Fix · GHSA-hjpm-7mrm-26w8 better-auth (npm) Fixed in 1.1.20 Advisory →

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-27143
  2. 2026-10-03 Alias added: GHSA-hjpm-7mrm-26w8

References

Patch 2

Advisory 2

Other 3

  • TI-2026-38586 Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins CVSS 4.0CRITICAL 9.1
  • TI-2026-38587 Better Auth: Server-side request forgery via unvalidated OIDC endpoints on @better-auth/sso provider registration CVSS 3.1CRITICAL 9.6
  • TI-2026-38591 Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking CVSS 3.1HIGH 8.1
  • TI-2026-38590 Better Auth: Account takeover via OAuth auto-link to unverified pre-registered email CVSS 3.1HIGH 8.3
  • TI-2026-38592 Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption CVSS 4.0HIGH 7.6
  • TI-2026-38588 Better Auth: Unauthorized invitation acceptance via unverified email match in organization plugin CVSS 3.1HIGH 7.7
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences