Executive brief
Casdoor, an identity and access management platform, contains a security flaw in how it handles login requests from external identity providers. Because the system does not check if a login credential has been used before, an attacker who captures a previous login session can reuse it to gain unauthorized access. This allows an attacker to log in as any user, including administrators, without needing a password or multi-factor authentication.
Technical details
A vulnerability in Casdoor's SAML Service Provider (SP) implementation arises from a lack of replay protection in the ParseSamlResponse() function within object/saml_sp.go. The application fails to maintain an assertion ID cache or enforce 'OneTimeUse' conditions, meaning it does not track whether a specific SAML assertion has already been processed. An attacker can capture a valid SAML assertion and replay it to the Assertion Consumer Service (ACS) endpoint to establish a new authenticated session. This bypasses all authentication requirements, including passwords and MFA, and can be used to impersonate any subject in the assertion, including administrative accounts. As of the advisory date, no patch is available.
Affected products
- Casdoor Casdoor 2.362.0 and earlier
Timeline
- 2026-05-28: disclosed: Vulnerability disclosed by CERT/CC after unsuccessful coordination with the vendor.
- 2026-05-28: advisory: NVD published CVE-2026-9095.