CVE-2026-53513: better auth Input Validation Flaw — Fix

Description

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.

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CVSS v3.1 Score

9.6

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0025

Probability of exploitation

0.17%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-345 CWE-345

CWE-441 CWE-441

CWE-918 Server-Side Request Forgery (SSRF)

Affected Products

Vendor	Product	Versions
better-auth	better-auth\/sso	< 1.6.11
better-auth	better_auth	0.1.0 — 1.6.11

References

Advisories & Patches

https://github.com/better-auth/better-auth/commit/37f60cb176cb53147da7dfd5ec15afa5b486e81e https://github.com/better-auth/better-auth/pull/9574 https://github.com/better-auth/better-auth/security/advisories/GHSA-5rr4-8452-hf4v

Other References

https://github.com/better-auth/better-auth/releases/tag/v1.6.11

Frequently Asked Questions

What is CVE-2026-53513? +

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. It has a CVSS v3.1 base score of 9.6 (CRITICAL).

How severe is CVE-2026-53513? +

CVE-2026-53513 has a CVSS v3.1 score of 9.6 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0025, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-53513? +

CVE-2026-53513 affects products from better-auth, specifically: better-auth\/sso, better_auth. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-53513? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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