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Fencer Intel
critical 9.6

CVE-2026-53513 json

Better Auth: Server-side request forgery via unvalidated OIDC endpoints on @better-auth/sso provider registration

published 5mo ago modified last mo. also EUVD-2026-44733 , GHSA-5rr4-8452-hf4v

cvss
9.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 16%
public exploits
0
none known

Summary

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the @better-auth/sso plugin's POST /sso/register and POST /sso/update-provider endpoints accept attacker-controlled oidcConfig.userInfoEndpoint, tokenEndpoint, and jwksEndpoint URLs when skipDiscovery: true is set, store them on the ssoProvider row without origin validation, and fetch them during OIDC callback, allowing non-blind server-side request forgery and possible account linking when trustEmailVerified: true is configured. 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

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
3mo ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
GitHub 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
npm @better-auth/sso
>=0.1.0, <1.6.11
1.6.11

Affected products

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

Classification

Weakness
  • CWE-20 Improper Input Validation
  • CWE-345 Insufficient Verification of Data Authenticity
  • CWE-441 Unintended Proxy or Intermediary
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel 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.

The maintainers of better-auth/better-auth published their own advisory on GitHub. Reviewed sources take precedence over it.