ZITADEL: Missing authentication for MFA enrollment in Login V1
Summary
ZITADEL's hosted Login V1 UI accepts second-factor enrollment and initialization requests before the primary factor is verified. An attacker who knows only a victim's login name can register attacker-controlled TOTP, OTP-SMS, OTP-Email or U2F factors, overwrite the verified phone number and enumerate valid users through differing error messages. The flaw does not by itself allow account takeover, because the password is still required to log in. Applications that authenticate users through Login V1 are affected; Login V2 is not.
Affected
- ZITADEL 3.0.0 to 3.4.14
- ZITADEL 4.0.0 to 4.17.0
- Only deployments using the hosted Login V1 UI
Fixed in
- Upgrade to ZITADEL 4.17.1 or later (4.x)
- Upgrade to ZITADEL 3.4.15 or later (3.x)
Workaround
- Unknown. The vendor states that no configuration fully closes the gap on unpatched versions; upgrading is the only remedy.
Exploitation
- No known exploitation in the wild.
- No public proof of concept found at time of research.
- CISA SSVC: exploitation none, automatable yes, technical impact partial.
Our recommendation
- Identify all ZITADEL instances and their versions.
- Upgrade to 4.17.1 or later, or 3.4.15 or later.
- Check whether Login V1 is enabled and reachable, especially from the internet.
- Audit MFA factors and verified phone numbers for unexpected changes since October 4, 2026.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- GitHub Security Advisory GHSA-72q5-mv5c-vxv4 github.com
- VulnCheck Advisory www.vulncheck.com
- ZITADEL v4.17.1 Release Notes github.com
- VulDB CVE-2026-105210 vuldb.com
- HOL Guard CVE-2026-105210 hol.org
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 22:35.
Original description (NVD)
ZITADEL 3.x before 3.4.15 and 4.x before 4.17.1 contains a missing authentication flaw in the hosted Login V1 UI, whose second-factor enrollment and initialization handlers act on an identify-only session before any primary factor is verified. Attackers knowing only a victim's login name can enroll attacker-controlled TOTP, OTP-SMS, OTP-Email, or U2F factors, overwrite the verified phone number, and enumerate users through discrepant errors.
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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