CVE-2026-105207

CRITICAL 9.8

ZITADEL before 4.17.3 Account Takeover via External IdP Linking

CVSS Score

9.8

EPSS Score

0.0%

EPSS Percentile

0th

ZITADEL 3.0.0 through 3.4.15 and 4.0.0 before 4.17.3 creates links between user accounts and external identity providers without verifying a primary factor or the caller's permission, including on identify-only Login V2 sessions and via the User Service V2 AddIDPLink endpoint. An unauthenticated attacker knowing a victim's login name can bind their own external IdP identity to the victim's account and then sign in as the victim.

CWE	CWE-306
Vendor	zitadel
Product	zitadel
Published	Oct 4, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

zitadel / zitadel

0 < 4.17.3

zitadel / zitadel

0 ≤ 4.19.4

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/zitadel/zitadel/security/advisories/GHSA-g8gj-gq47-xgf4 vulncheck.com: https://www.vulncheck.com/advisories/zitadel-before-4.17.3-account-takeover-via-external-idp-linking

Credits

🔍 lucasdodgson 🔍 AdamKorcz grvijayan livio-a