CVE-2026-53515Public exploitNetwork attack vector

Unauthorized membership creation via unchecked SSO registration

Published Jul 15, 2026 · Updated Jul 15, 2026

Incorrect authorization in Better Auth and its SSO Plugin 1.2.10 through 1.6.10 allows remote authenticated users to add organization members. The POST /sso/register handler verifies only that the caller has a membership row and never requires the owner or admin role before storing an organization-linked OIDC or SAML provider. Exploitation requires both SSO and organization plugins, enabled user registration, and regular organization membership; callbacks can provision asserted users, with admin access only when the configured default role grants it.

CVSS severity7.1
High
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Better Auth and its SSO Plugin 1.2.10 through 1.6.10 allows remote authenticated users to add organization members. The POST /sso/register handler verifies only that the caller has a membership row and never requires the owner or admin role before storing an organization-linked OIDC or SAML provider. Exploitation requires both SSO and organization plugins, enabled user registration, and regular organization membership; callbacks can provision asserted users, with admin access only when the configured default role grants it.

The record

CVE
CVE-2026-53515
Published
Jul 15, 2026
Updated
Jul 15, 2026
Vendor
Better Auth
Product
Better Auth
Classifications
CWE-269, CWE-285, CWE-863, T1136
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 1.2.10, < 1.6.11

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Better Auth · Better Authversion=>= 1.2.10, < 1.6.11
Better Auth · Better Auth SSO Pluginversion=>= 1.2.10, < 1.6.11

Published CVSS scores

7.1GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-269Improper Privilege Management
CWE-285Improper Authorization
CWE-863Incorrect Authorization
T1136Create Account

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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