CVE-2026-55789: Logto-Io Logto

High severity, CVSS 8.5. EPSS: 0.4% chance of exploitation in the next 30 days.

Logto is the modern, open-source auth infrastructure for SaaS and AI apps. Prior to 1.41.0, Logto's self-hosted SAML application IdP built the signed SAML response and assertion by string-substituting user-controlled profile attributes such as name, email, and custom attribute-mapping values into element-text placeholders of a SAML XML template using samlify 2.10.0, which left those placeholders unescaped. An authenticated low-privilege user could place XML markup in a profile attribute so Logto signed a forged SAML attribute, such as an arbitrary role, allowing privilege escalation at relying Service Providers that authorize on SAML attributes. This issue is fixed in version 1.41.0.

Affected products

• Logto-Io Logto: before 1.41.0 (fixed in 1.41.0)

Published 2026-07-10. Last modified 2026-07-13.