CVE-2026-56739 Logto: SSRF via Webhooks and Custom OAuth2 Connector UserInfo Endpoint
Administrators can trigger Server-Side Request Forgery via webhooks or OAuth connectors, potentially exposing internal data or credentials.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-56739?
CVE-2026-56739 is a high-severity server-side request forgery vulnerability in logto-io logto, published on 24 Sep 2026. An attacker needs administrator access to exploit it, with no action from the victim.
Official description
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.
Weakness: CWE-918
Which versions are affected by CVE-2026-56739?
How do I fix CVE-2026-56739?
No fix has been published for CVE-2026-56739 yet. Limit exposure of the affected software until one is available.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-56739 being exploited?
There is no known exploitation of CVE-2026-56739 in the wild and no public exploit code.
Sources
Also known as GHSA-3556-624q-c5w3.