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Fencer Vulns
high 7.1

CVE-2026-53515 json

Better Auth: Privilege escalation via SSO provider registration: missing admin role check in @better-auth/sso

published 2026-07-15 3 mo ago modified 2026-07-21 3 mo ago also GHSA-gv74-j8m3-fg5f , EUVD-2026-44740

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

Better Auth is an authentication and authorization library for TypeScript. From 1.2.10 until 1.6.11, the @better-auth/sso plugin's POST /sso/register endpoint lets any organization member attach a new SSO provider to that organization because registerSSOProvider checks only for a membership row and does not require an owner or admin role, allowing attacker-controlled OIDC or SAML providers to drive /sso/callback/{providerId} organization provisioning. This issue is fixed in version 1.6.11.

Patch / fix

  • npm @better-auth/sso 1.6.11
  • better-auth better-auth/sso 1.6.11
  • better-auth better_auth 1.6.11

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N
GitHub 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm @better-auth/sso
>=1.2.10, <1.6.11
1.6.11

Affected products

  • better-auth better-auth
  • @better-auth sso

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.