CVE-2026-110862 better-auth CVE debrief

Who should care

Defenders responsible for Better Auth deployments, particularly those using versions between 1.4.0-beta.18 and 1.7.7, should assess exposure and apply remediation. This includes developers, security teams, and IT professionals managing OAuth and Magic Link configurations.

Why it matters

The CVE-2026-110862 vulnerability in Better Auth versions 1.4.0-beta.18 before 1.7.7 allows unauthenticated attackers to bypass authentication, potentially leading to unauthorized access, account creation, or session hijacking. Defenders should prioritize verifying exposure, assessing OAuth and Magic Link configurations, and applying vendor remediation.

• Potential unauthorized access to user accounts
• Possible creation of falsely email-verified accounts
• Risk of session hijacking or unauthorized session creation
• Need for verification of OAuth and Magic Link configurations

Technical summary

The Better Auth library versions 1.4.0-beta.18 before 1.7.7 contain an authentication bypass vulnerability. This vulnerability allows unauthenticated attackers to sign in as other users by reusing OAuth state values as Magic Link tokens. An attacker can start an OAuth sign-in with a victim's email and submit the returned state to Magic Link verification, gaining sessions or creating falsely email-verified accounts.

Defensive priority

Defenders should prioritize verifying exposure of Better Auth versions between 1.4.0-beta.18 and 1.7.7, assessing OAuth and Magic Link configurations, and applying vendor remediation.

Recommended defensive actions

• Verify exposure of Better Auth versions between 1.4.0-beta.18 and 1.7.7
• Assess OAuth and Magic Link configurations
• Apply vendor remediation to update to version 1.7.7 or later
• Monitor for unauthorized access attempts
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on the authentication bypass vulnerability in Better Auth versions 1.4.0-beta.18 before 1.7.7. The vulnerability allows unauthenticated attackers to sign in as other users by reusing OAuth state values as Magic Link tokens.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.