CVE-2026-110864

Better Auth 1.5.0-beta.12 before 1.7.7 Authentication Bypass via OAuth Proxy

At a glance

Severity: CRITICAL 9.1
EPSS: EPSS 0.29 % · percentile 21 (2026-10-27)
State: PUBLISHED
Published: 2026-10-14
Updated: 2026-10-15
Assigner: VulnCheck
NVD status: Deferred

Description

Better Auth from 1.5.0-beta.12 before 1.7.7 contains an authentication bypass vulnerability in the OAuth Proxy plugin that allows unauthenticated attackers to sign in as other users by forging encrypted profiles. When the proxy shares the global secret and cookie-stored state is used, attackers can obtain encrypted state for a fake profile with a victim's verified email to take over the account via implicit linking.

Scores

Version	Score	Vector	Scored by
CVSS 4.0	CRITICAL 9.1	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N	VulnCheck
CVSS 3.1	HIGH 7.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N	VulnCheck
CVSS 4.0	CRITICAL 9.1	CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X	NVD · disclosure@vulncheck.com (Secondary)
CVSS 3.1	HIGH 7.4	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N	NVD · disclosure@vulncheck.com (Secondary)

Weaknesses (CWE)

CWE-287

Advisories

GHSA-r4xp-prcw-77qf — better-auth: OAuth Proxy lets an attacker sign in as another user

European references

ENISA EUVD · EUVD-2026-101747
GCVE · GCVE-0-2026-110864

Affected products

Product	Versions
better-auth · better-auth	affected 1.5.0-beta.12 < 1.7.7 ; unaffected 1.7.7

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD