External risk intelligence

SuggestArr Authentication Bypass via Spoofed X-Forwarded-For Header.

CVE advisorySeverity: CRITICAL (CVSS 9.1)

CVE-2026-113703

The vulnerability resides in an API service that relies on headers to determine authentication. Such services are commonly exposed as web-facing APIs. Because the application processes network requests and is susceptible to header-based manipulation, it is frequently deployed in internet-facing configurations where edge proxies or load balancers interact with external traffic.

Authentication Bypass

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 vulnerability has been identified in SuggestArr's local authentication mode, allowing unauthenticated administrative access by manipulating network request headers. This bypass could grant attackers full control over sensitive administrative functions, such as user and job management, without needing valid credentials. The main concern is confirming relevance and exposure within our environment.

Bypass authentication by faking trusted network addresses.
Grants unauthorized administrative control over core functions.
Confirm if this technology is deployed and exposed.

Attack Path

How an attacker could exploit the issue

An attacker can bypass authentication by sending a specially crafted network request. This request exploits how the application handles proxy configurations and trusted IP addresses to trick the system into granting administrative access without any credentials. Once authenticated, the attacker can access sensitive endpoints and perform administrative actions.

Network access required.
Spoofed X-Forwarded-For header triggers bypass.
Unauthenticated administrative access.

Live Threat

Current exploitation, exposure, and threat context

When supported by the advisory's configuration, this vulnerability could allow an unauthenticated attacker to bypass authentication controls by spoofing the `X-Forwarded-For` header. This could grant administrative access to sensitive API endpoints, potentially enabling unauthorized control over user accounts and job data.

Administrative API access and sensitive data.
Spoofing `X-Forwarded-For` header when supported.
Unauthorized control over user and job data.

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability in SuggestArr's authentication bypass could impact application owners or platform teams responsible for managing the API, as well as network and security teams overseeing traffic ingress. The initial step should be to identify all instances of the affected technology, confirm their exposure and criticality, and then determine the accountable owner before planning remediation.

Application or platform teams own remediation.
Verify external access and impact.
Plan coordinated vendor engagement.

Supplementary metadata

CVSS vector

Validate whether this threat affects your internet-facing exposure.

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Frequently asked questions

What is SuggestArr and how is it used?

SuggestArr is a software application that provides services for managing and automating requests or suggestions, often interacting with media or job-processing pipelines. It includes an API service layer that facilitates administrative tasks like user management and job monitoring, which typically requires robust authentication to ensure only authorized individuals can modify system settings.

What is the vulnerability in CVE-2026-113703?

This is an authentication bypass vulnerability, classified as CWE-290. It occurs because the application incorrectly trusts the 'X-Forwarded-For' HTTP header when determining the user's origin. By manipulating this header, an attacker can trick the system into believing a request is coming from a trusted local address, successfully skipping the login process to gain full administrative privileges.

How does an attacker trigger this authentication bypass?

An attacker triggers the flaw by sending a network request to the API with a spoofed 'X-Forwarded-For' header set to a trusted IP address, such as 127.0.0.1. The bug does not trigger if the application is correctly configured to ignore these headers or if it does not rely on local network address trust to grant administrative sessions.

Why should I worry about CVE-2026-113703 in my network?

Halo Surface Signal indicates this vulnerability resides in an API service often deployed in internet-facing configurations. Because the software relies on headers for authentication, it is highly susceptible to external manipulation. If your instance is reachable from the internet or sits behind a load balancer that passes these headers, unauthorized parties may be able to interact with your administrative endpoints without credentials.

What are the first steps to secure my SuggestArr instance?

Begin by identifying all running instances of SuggestArr within your environment to confirm where the software is deployed. Review your current network architecture to see if these services are exposed to external traffic. Once you have an inventory, coordinate with your platform or application teams to update the software to version 3.0.0 or later, which addresses the improper trust placed in the forwarded header.

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.