CVE-2026-36758 in Halo
Summary
by MITRE • 04/30/2026
A Server-Side Request Forgery (SSRF) in the /themes/-/install-from-uri endpoint of halo v2.22.14 allows authenticated attackers to scan internal resources via a crafted GET request.
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Analysis
by VulDB Data Team • 06/17/2026
Server-Side Request Forgery vulnerabilities represent a critical class of security flaws that enable attackers to manipulate server-side applications into making unintended requests to internal systems. The specific vulnerability discovered in halo v2.22.14 affects the /themes/-/install-from-uri endpoint, which serves as a legitimate interface for installing themes from remote URIs. This endpoint lacks proper input validation and sanitization mechanisms, creating an exploitable pathway for authenticated attackers to leverage the application's trust relationship with internal services. The flaw exists because the application accepts user-supplied URI parameters without adequate restrictions on the protocols that can be used or the destinations that can be accessed, effectively allowing arbitrary internal resource access through the server's network connections.
The technical implementation of this vulnerability stems from insufficient validation of the URI parameter provided in the GET request to the /themes/-/install-from-uri endpoint. When an attacker submits a crafted URI, the application processes it without verifying whether the target is a valid external resource or an internal system. This oversight creates a dangerous attack surface where malicious actors can construct requests that target internal services such as databases, configuration servers, or other internal APIs that may be accessible from the application server. The vulnerability is particularly concerning because it requires only authentication to exploit, meaning that any authenticated user with access to the theme installation functionality can potentially perform internal network scanning and reconnaissance activities.
The operational impact of this SSRF vulnerability extends beyond simple information disclosure to encompass comprehensive internal network reconnaissance and potential privilege escalation. Attackers can utilize this flaw to scan internal network ranges, identify running services, and potentially discover sensitive internal systems that would normally be protected by network segmentation. The vulnerability enables attackers to perform port scanning against internal hosts, access internal APIs that may contain sensitive data, and potentially exploit other vulnerabilities within the internal network infrastructure. This capability significantly increases the attack surface for organizations using affected halo versions, as it allows for systematic exploration of internal resources that would otherwise be isolated from external access. The impact is further amplified by the fact that the application's internal trust relationships may grant access to sensitive systems that are not properly secured against internal threats.
Security mitigations for this vulnerability should focus on implementing strict input validation and protocol restrictions within the application's URI handling mechanisms. Organizations should implement comprehensive URI validation that rejects requests to internal network addresses, loopback interfaces, and private IP ranges that are not explicitly allowed. The application should enforce a whitelist of acceptable protocols and destinations, ensuring that only trusted external resources can be accessed through the theme installation functionality. Additionally, network-level protections such as firewall rules and internal network segmentation should be implemented to limit the potential impact of successful exploitation attempts. The remediation process should include comprehensive testing to ensure that all URI parameters are properly validated and that the application's trust relationships with internal services are appropriately restricted. Organizations should also consider implementing network monitoring and logging to detect anomalous patterns of internal resource access that may indicate exploitation attempts. This vulnerability aligns with CWE-918, which specifically addresses Server-Side Request Forgery, and represents a significant risk in the context of the ATT&CK framework under the reconnaissance and initial access phases, where adversaries seek to map network environments and identify exploitable systems.