CVE-2026-16910 in OpenShift Update Service
Summary
by MITRE • 07/24/2026
A flaw was found in Red Hat Quay's notification webhook feature. The Slack and generic webhook notification handlers accept user-supplied URLs without SSRF validation, allowing a repository administrator to make the Quay worker issue POST requests to internal network addresses or cloud infrastructure endpoints that should not be reachable from the application.
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Analysis
by VulDB Data Team • 07/24/2026
This vulnerability exists within Red Hat Quay's notification webhook functionality where the Slack and generic webhook handlers fail to validate user-provided URLs against server-side request forgery attacks. The flaw allows malicious actors with repository administrator privileges to craft specially formatted URLs that bypass normal network restrictions and enable the Quay worker process to initiate POST requests to internal network addresses or cloud infrastructure endpoints that should remain isolated from external application access. This represents a critical security oversight in the application's input validation mechanisms and demonstrates a failure to implement proper SSRF (Server-Side Request Forgery) protections within the notification handling components.
The technical exploitation of this vulnerability occurs when an attacker with repository administrator rights configures a webhook notification pointing to an internal endpoint such as cloud metadata services, internal APIs, or other sensitive infrastructure components. The Quay worker process, running with elevated privileges and typically having network access to internal systems, will then execute the configured POST request without validating whether the target address is appropriate or safe for external access. This creates a pathway for attackers to potentially exfiltrate sensitive information from internal services, perform unauthorized operations against cloud metadata endpoints, or gain insights into the internal network topology through response data returned by these internal systems.
The operational impact of this vulnerability extends beyond simple information disclosure as it enables potential lateral movement within an organization's infrastructure. Attackers could leverage this flaw to access cloud instance metadata services such as AWS EC2 metadata endpoints, Azure Instance Metadata Service, or other cloud provider-specific endpoints that contain sensitive credentials and configuration data. Additionally, the vulnerability allows for internal network reconnaissance where attackers can probe internal services for open ports, running applications, and system information that would normally be protected by network segmentation and firewall rules. This represents a significant escalation of privileges from repository administrator access to potential full infrastructure compromise through indirect means.
Organizations using Red Hat Quay should immediately implement URL validation mechanisms that prevent notification webhook handlers from accepting internal IP addresses, loopback addresses, or private network ranges as target endpoints. The solution involves implementing strict validation of user-supplied URLs against known safe domains and applying network restrictions that prevent the application from accessing internal infrastructure directly through webhook functionality. Security teams should also consider implementing network segmentation controls to limit what internal services can be accessed by the Quay worker process, while also monitoring webhook configuration changes for suspicious patterns. This vulnerability aligns with CWE-918 Server-Side Request Forgery and maps to ATT&CK technique T1071.004 Application Layer Protocol: DNS, though the specific implementation focuses on notification handlers rather than standard network protocols.
The remediation approach requires comprehensive input validation of all webhook URLs through a combination of domain whitelisting, IP address range filtering, and network access control measures that prevent direct communication between the Quay worker process and internal infrastructure. Organizations should also implement automated monitoring for unauthorized webhook configuration changes and establish security policies that restrict who can configure notification endpoints within their Quay deployments. Regular security assessments should verify that no similar vulnerabilities exist in other notification or integration components of the platform, as this type of flaw represents a common pattern in application development where external input is not properly validated against internal access restrictions.