CVE-2026-63203

Logto before version 1.43.0 fetches administrator-controlled outbound destinations without validating the connection address. Webhook delivery and custom/OIDC connectors can reach special-use and cloud metadata addresses, potentially exposing internal data or upstream provider credentials. This issue is fixed in version 1.43.0.

Logto performs principal lookup without normalizing email and identifier strings, enabling principal collision and unauthorized account access via case- or Unicode-different identities.

Logto does not enforce locally configured MFA during SSO authentication, allowing users to bypass second-factor requirements and grants unauthorized access.

Logto bypasses OIDC nonce validation when the nonce claim is absent from the id_token, enabling replay of authentication tokens and weakening session-binding.

Logto allows unverified email-based SSO account linking, enabling an attacker to register an identity at a permissive IdP using a victim’s email and gain unauthorized access to the victim’s account.

Logto through 1.42.0 contains a server-side request forgery vulnerability in the OIDC SSO connector creation endpoint that fails to validate the issuer URL parameter. Tenant administrators with Management API credentials can supply arbitrary internal URLs to trigger HTTP GET requests to private network services, with response content returned in API responses.

Logto through 1.42.0 contains a server-side request forgery vulnerability in the POST /api/hooks/:id/test endpoint that accepts arbitrary URLs without host validation. Tenant administrators with Management API tokens can make the server issue HTTP POST requests to internal URLs and retrieve response bodies from services on the private network.

Logto, the modern open-source auth infrastructure, versions 1.40.1 to 1.41.0, has a vulnerability in GitHub Actions workflow where the pull request title is directly interpolated into an echo command in the commitlint step. A title containing a single quote can terminate the echo string and append arbitrary shell commands on the runner. An attacker can disrupt the ephemeral workflow execution, but repository secrets are not exposed.

Logto before version 1.41.0 has a catastrophic backtracking vulnerability in the regular expression used for email subaddressing blocking. An attacker can send a specially crafted email address, causing an event-loop stall and making authentication services unavailable.

Logto omits validation of the SAML <Conditions> element, enabling attackers to strip time and audience restrictions and replay assertions indefinitely.