High severity · published Oct 4, 2026
CVE-2026-105211
ZITADEL before 4.17.1 Authentication Bypass via Login V2 OTP returnCode
8.1
CVSS
0.3%
EPSS
No
On KEV
Description
ZITADEL before 4.17.1 contains an authentication bypass vulnerability in Login V2 that allows unauthenticated attackers to take over accounts by obtaining OTP codes via the returnCode delivery type. Attackers knowing a login name of a victim with OTP-Email and OTP-SMS enrolled can read both codes from server-action responses to gain MFA-authenticated sessions, including administrator takeover.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 26% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
ZI
zitadel · zitadel
before 4.17.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-105211
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-105211
vendor-advisory
https://github.com/zitadel/zitadel/security/advisories/GHSA-3gwm-5wx8-4gm6
third-party-advisory
https://www.vulncheck.com/advisories/zitadel-before-4.17.1-authentication-bypass-via-login-v2-otp-returncode
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