High 8.5Published Sep 24, 2026

CVE-2026-56739Logto: SSRF via Webhooks and Custom OAuth2 Connector UserInfo Endpoint

Updated under an hour ago (2026-10-19 08:23 UTC)

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It affects logto-io logto. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 8.5 HIGH (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:L/VA:L/SC:H/SI:H/SA:H
Weakness (CWE): CWE-918
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Sep 28, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

logto-io logto logto_io:logto (from the name)	before 1.43.0	CNA record

References

https://github.com/logto-io/logto/security/advisories/GHSA-3556-624q-c5w3x-refsource-confirm
https://github.com/logto-io/logto/pull/9501x-refsource-misc
https://github.com/logto-io/logto/commit/16f4b2e732d5114ac98646c9370ec6ab61d6ed26x-refsource-misc
https://github.com/logto-io/logto/releases/tag/v1.43.0x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.