External risk intelligence

Guardrails Detectors Blind SSRF via XML Schema Definition

CVE advisorySeverity: CRITICAL (CVSS 9.3)

CVE-2026-15378

The component is a detector often integrated into web applications, APIs, or data processing pipelines that handle user-supplied input. SSRF vulnerabilities in these contexts are commonly reachable through internet-facing interfaces that process XML or external definitions, allowing attackers to leverage the service to probe internal network resources.

Server-Side Request Forgery

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

A critical vulnerability has been identified in the `guardrails-detectors` component, allowing remote attackers to exploit a blind Server-Side Request Forgery. This flaw could enable unauthorized access to sensitive internal network resources and local files, posing a significant risk to data integrity and confidentiality.

Attackers can exploit a flaw to access internal systems.
Risk of unauthorized access to sensitive data.
Confirm relevance and assess potential exposure.

Attack Path

How an attacker could exploit the issue

An attacker can initiate a blind Server-Side Request Forgery (SSRF) by sending a malicious XML Schema Definition (XSD) to the `guardrails-detectors` component. This flaw does not require any specific user privileges or interaction and can be exploited remotely. Successful exploitation could allow the attacker to access sensitive internal information or read local files.

No authentication or user interaction needed.
Submitting crafted XML Schema Definition.
Unauthorized information access and file reads.

Live Threat

Current exploitation, exposure, and threat context

A remote attacker could exploit this flaw by sending a malicious XML Schema Definition (XSD) to the `guardrails-detectors` component. When the component processes this crafted input, it could be tricked into making requests to internal network resources. This could potentially expose sensitive information like cloud credentials, Kubernetes API details, internal MinIO endpoints, and allow reading local files such as service account tokens and pod secrets.

Sensitive cloud and internal credentials.
Remote unauthenticated request forging.
Exposure of service account tokens.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in the `guardrails-detectors` component could allow remote attackers to access sensitive internal information or local files by submitting a crafted XSD string, enabling blind Server-Side Request Forgery. The initial focus should be on identifying all instances of the affected component, determining their exposure and business criticality, locating the accountable owner, and then prioritizing remediation efforts.

Application and platform teams own the issue.
Verify component exposure and data criticality.
Plan and coordinate remediation actions.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is the guardrails-detectors component?

Guardrails-detectors is a specialized software component designed to analyze data inputs, often integrated into web applications, APIs, or data processing pipelines. It is commonly used to validate or inspect incoming information to ensure it adheres to predefined security or structural rules before the data is processed by the broader system.

What does CWE-918 mean in the context of CVE-2026-15378?

CWE-918 refers to Server-Side Request Forgery (SSRF). In this specific vulnerability, the software fails to properly validate a user-supplied XML Schema Definition (XSD). Because the component is tricked into trusting this malicious input, it can be manipulated to send unauthorized requests to internal network locations or read local system files that the component should not be accessing.

How is this SSRF vulnerability triggered?

An attacker triggers this flaw by submitting a specially crafted XML Schema Definition (XSD) string to the component. It is important to note that the vulnerability is not triggered by standard, legitimate XML processing or benign schema validation. Exploitation requires the specific, malicious structure within the XSD designed to force the software to make unintended network requests or file system calls.

Is my system at risk according to Halo Surface Signal?

Halo Surface Signal indicates that systems are most at risk if the guardrails-detectors component is integrated into interfaces that are internet-facing. Because these interfaces process user-supplied input like XML, they provide a path for an attacker to reach internal network resources. If your deployment uses this component in a pipeline that accepts external definitions, the likelihood of this flaw being reachable is higher.

What are the first steps to address this CVE?

Start by identifying all applications or services in your environment that utilize the guardrails-detectors component. Once located, verify if these services process external XML input and evaluate their network reachability. Coordinate with the relevant development or platform teams to prioritize these instances based on the sensitivity of the data they access, such as cloud credentials or Kubernetes secrets, and prepare for necessary updates or configuration changes.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.