CVE-2026-73087 in Dozzle
Summary
by MITRE • 08/12/2026
Dozzle is a realtime log viewer for docker containers. From 10.5.2 until 10.6.15, the isBlockedIP SSRF guard in internal/notification/dispatcher/webhook.go, used by safeDialContext for webhook notification URLs, does not inspect IPv4 addresses embedded in 6to4, NAT64, Teredo, or IPv4-compatible IPv6 addresses, allowing an authenticated user to reach loopback or link-local targets that the guard intends to block. This issue is fixed in version 10.6.15.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability described represents a sophisticated server-side request forgery flaw within Dozzle's webhook notification system that emerged between versions 10.5.2 and 10.6.15. This security weakness specifically targets the isBlockedIP function located in internal/notification/dispatcher/webhook.go, which serves as a critical access control mechanism designed to prevent unauthorized connections to sensitive network addresses. The flaw stems from insufficient validation of IPv6 addresses that contain embedded IPv4 addresses through various tunneling mechanisms including 6to4, NAT64, and Teredo protocols, creating a pathway for authenticated attackers to bypass intended security restrictions.
The technical implementation of this vulnerability exploits the inherent complexity of IPv6 addressing where certain address types can contain IPv4 addresses within their structure. When the safeDialContext function processes webhook URLs, it fails to properly deconstruct and validate IPv6 addresses that employ tunneling mechanisms such as 6to4 (which embeds IPv4 addresses in the upper 32 bits of IPv6 addresses) or NAT64 (which translates IPv4 addresses into IPv6 format). This oversight allows an authenticated user to craft webhook URLs that appear to target external addresses while actually routing through internal network segments, effectively circumventing the IP blocking mechanism designed to prevent access to loopback addresses like 127.0.0.1 or link-local addresses such as fe80::1.
From an operational perspective, this vulnerability creates significant risk for organizations relying on Dozzle for container monitoring and log management. An authenticated attacker with access to the Dozzle application can potentially access internal services that would normally be restricted from external reach, including localhost services, internal APIs, or other network resources accessible through loopback interfaces. The impact extends beyond simple information disclosure to potential privilege escalation opportunities, as attackers could leverage this bypass to access sensitive internal systems that might not be properly protected by traditional network segmentation measures.
The vulnerability aligns with CWE-918, Server-Side Request Forgery (SSRF), which specifically addresses the issue of an attacker's ability to manipulate a server's request to interact with unexpected destinations. This flaw also maps to ATT&CK technique T1071.004, Application Layer Protocol: DNS, as it involves manipulation of network protocols and address resolution mechanisms. The security implications are particularly concerning given that Dozzle operates as a monitoring tool for containerized environments where the internal network topology may contain numerous services with varying levels of sensitivity and access controls.
Organizations should implement immediate mitigation strategies including updating to version 10.6.15 or later, which contains the necessary fixes for proper IPv6 address validation. Additionally, administrators should review webhook configurations to ensure that only trusted external endpoints are configured, implement network segmentation to isolate monitoring tools from critical internal services, and consider deploying network-level firewalls to restrict outbound connections from the Dozzle application. The fix implemented in version 10.6.15 likely involves enhanced IPv6 address parsing and validation logic that properly identifies and blocks tunneling mechanisms while maintaining legitimate external connectivity for webhook notifications.