CVE-2026-56739: Logto: SSRF via Webhooks and Custom OAuth2 Connector UserInfo Endpoint
Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.43.0, Logto fetches administrator-controlled outbound destinations without validating the address used for the connection. Webhook delivery in packages/core/src/libraries/hook/utils.ts can reach special-use and cloud metadata addresses. Custom OAuth2 connectors can use an attacker-selected userInfoEndpoint and forward the OAuth access token in the Authorization header, while OIDC connectors can fetch an attacker-selected jwksUri. The affected operations require tenant administrative configuration access, but they cross the server's network boundary and can expose internal data or upstream provider credentials. This issue is fixed in version 1.43.0.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Logtoto a version that resolves this vulnerability.Fixed in 1.43.0
Event History
Frequently Asked Questions
Who can exploit this issue?
Exploitation requires tenant administrative configuration access. An administrator, or anyone who compromises an administrator account, can configure outbound webhook destinations or connector endpoints that cause the Logto server to make requests across its network boundary.
Which features create the outbound request risk?
Webhook delivery can be configured to reach special-use and cloud metadata addresses. Custom OAuth2 connectors can use an attacker-selected userInfoEndpoint and send the OAuth access token in the Authorization header, while OIDC connectors can fetch an attacker-selected jwksUri.
What could be exposed through exploitation?
The issue can expose internal data reachable from the Logto server. For custom OAuth2 connectors, it can also expose upstream provider credentials because the OAuth access token is forwarded to the configured userInfo endpoint.
How can this be remediated?
Upgrade Logto to version 1.43.0, which fixes the issue.