Authentication Bypass in Express Gateway OAuth 2.0 Refresh Token Grant

CVE-2026-107162

What is CVE-2026-107162?

Express Gateway versions up to 1.16.11 are susceptible to an authentication bypass vulnerability within the OAuth 2.0 refresh token grant mechanism. The flaw occurs due to inadequate validation of the token secret and the issuing client. This allows attackers with legitimate client credentials and the identifier of another user’s refresh token to retrieve that user’s access token. Consequently, they can impersonate the user when accessing OAuth2-protected APIs, posing a significant security risk. Developers and users of Express Gateway are urged to update to a patched version to mitigate this vulnerability.

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