Insecure Default Initialization of Resource Affecting better-auth package, versions <1.6.11
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JS-BETTERAUTH-17889826
- published8 Jul 2026
- disclosed7 Jul 2026
- creditsubhan umer
Introduced: 7 Jul 2026
CVE-2026-67336 (opens in a new tab)How to fix?
Upgrade better-auth to version 1.6.11 or higher.
Overview
better-auth is a The most comprehensive authentication library for TypeScript.
Affected versions of this package are vulnerable to Insecure Default Initialization of Resource in the oidcProvider. An attacker can gain unauthorized access or impersonate users by exploiting insecure cryptographic defaults, such as the acceptance of unsigned tokens and the use of weak PKCE methods.
Note: This is only exploitable if the application enables the legacy plugins and the relying parties do not pin to a specific signing algorithm or if the authorization URL is exposed to parties other than the user agent and the application's OP.
Workaround
This vulnerability can be mitigated by explicitly disabling plain PKCE by setting oidcProvider({ allowPlainCodeChallengeMethod: false }) and overriding the metadata to remove "none" from id_token_signing_alg_values_supported.