CVE-2026-55671 is a low-severity server-side request forgery (SSRF) vulnerability in github.com/zitadel/zitadel (go), affecting versions < 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2. It is fixed in 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2.
Summary A Server-Side Request Forgery (SSRF) vulnerability was discovered in Zitadel affecting: HTTP Notification Channels: Used as an alternative to SMTP/Twilio configurations, sending payloads to user-defined URLs via HTTP POST webhooks. OIDC BackChannel Logout: Terminates sessions across different applications. When a session ends, the Zitadel server sends an HTTP POST request to configured endpoints. SAML Metadata URL Fetches: Fetches SAML metadata configurations from user-provided external URLs. User-defined URLs in these components were not properly validated against an internal denylist, allowing potentially malicious URLs to bypass restrictions. Furthermore, the existing denylist mechanism previously introduced for Actions was found to be vulnerable to DNS rebinding, HTTP redirects, and protocol downgrades (HTTPS to HTTP), and it missed several common local network default entries. Because an attacker can supply arbitrary URLs, including loopback addresses, internal IPs, or cloud link-local addresses, they could potentially gather internal network architecture details, scan internal ports, or interact with unauthorized internal services and infrastructure. Impact When a user-supplied URL points to a local host or internal IP address, an adversary can perform a Server-Side Request Forgery (SSRF) attack. This allows them to map internal network structures and exploit exposed internal services. By leveraging DNS rebinding, an attacker could also bypass standard DNS-level checks, creating Time-of-Check to Time-of-Use (TOCTOU) gaps to access restricted internal endpoints. Additionally, vulnerabilities to HTTP redirects and protocol downgrades could allow attackers to manipulate the request flow or intercept sensitive communication. Notably, if Zitadel is deployed within cloud environments (such as AWS, GCP, or Azure) that still permit legacy IMDSv1 or unauthenticated cloud metadata endpoints (169.254.169.254), an attacker could theoretically attempt to target these metadata services. While Zitadel expects specific schemas or response formats for these features (which inherently limits data exfiltration capabilities and reduces the severe execution of the threat vector), users are strongly advised to patch immediately. Affected Versions Systems running one of the following versions are affected: 4.x: 4.0.0 through 4.15.1 (including RC versions) 3.x: 3.0.0 through 3.4.11 (including RC versions) Patches The vulnerability has been addressed in the latest releases. The patch resolves the issue by securely validating target URLs against a hardened denylist. By default, localhost, loopback IPs, and standard internal network blocks are denied. Note on Backports: This fix was only released on v4.x. While some of the affected components were generally available (GA), backporting the security fix to v3.x was not feasible due to the extensive code refactoring required to implement the unified network client securely. Please check the workarounds section if an upgrade to v4.x is not immediately possible. 4.x: Upgrade to $\ge$4.15.2 3.x: Update to $\ge$v4.15.2 or check out workarounds Workarounds The recommended solution is to update Zitadel to a patched version. If an immediate upgrade is not possible, you can mitigate the risk by implementing strict network policies, egress firewalls, or reverse proxy rules within your infrastructure to block Zitadel from initiating outbound connections to your internal network, loopback interfaces, or cloud metadata endpoints. Note that managing these network controls is outside the scope of Zitadel's native configurations. Questions If you have any questions or comments about this advisory, please email us at [email protected] Credits Thanks to everyone who reported this or a part of the vulnerability: cwanglab wooseokdotkim ffulbtech 0xBassia 5ud0 from Tarmo Technologies alanturing881 dungNHVhust and sondt99 oduoke567 DavidCarliez eddieran tikket1 Wernerina morimori-dev vamsik2k5
Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.
go
github.com/zitadel/zitadel (< 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2)github.com/zitadel/zitadel → 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2 (go)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Upgrade github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2 or later to resolve this vulnerability.
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-55671 is a low-severity server-side request forgery (SSRF) vulnerability in github.com/zitadel/zitadel (go), affecting versions < 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2. It is fixed in 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
github.com/zitadel/zitadel (go) versions < 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2 is affected.
Yes. CVE-2026-55671 is fixed in 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2. Upgrade to this version or later.
Whether CVE-2026-55671 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade github.com/zitadel/zitadel to 1.80.0-v2.20.0.20260615133614-8e82ec1cb9a2 or later.