CVE-2025-50578: Heimdall Application Vulnerable to Host Header Injection and Open Redirect
Heimdall, a popular web application dashboard, is susceptible to a critical security flaw that could allow attackers to compromise users and the application itself. Let's dive into the details.
Vulnerability Details
- CVE ID: CVE-2025-50578
- Description: LinuxServer.io heimdall version 2.6.3-ls307 is vulnerable to Host Header Injection and Open Redirect attacks due to insufficient validation of user-supplied HTTP headers, specifically `X-Forwarded-Host` and `Referer`.
- CVSS Score: 9.8 (Critical)
- CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CVSS Explanation: This score indicates a critical vulnerability. An attacker can remotely exploit this without authentication or user interaction, leading to complete compromise of confidentiality, integrity, and availability.
- Exploit Requirements: The attacker needs to send crafted HTTP requests to the Heimdall application. No authentication is required.
- Affected Vendor: LinuxServer.io
- Affected Product: Heimdall
- Affected Version: 2.6.3-ls307
- CWE: CWE-20 (Improper Input Validation), CWE-74 (Injection), CWE-601 (URL Redirection to Untrusted Site ('Open Redirect'))
- Explanation: These CWEs relate to the application's failure to properly sanitize user input. Specifically, trusting untrusted data in HTTP headers can allow an attacker to inject malicious code or redirect users to malicious sites.
Timeline of Events
- 2025-07-30: CVE ID assigned and vulnerability publicly disclosed.
- 2025-07-30: Initial analysis and reports emerge.
- TBD: Patch or mitigation released (awaiting analysis).
Exploitability & Real-World Risk
This vulnerability is highly exploitable due to its ease of execution. An attacker can craft malicious links or embed them in phishing emails, redirecting users to attacker-controlled sites after they interact with the legitimate Heimdall application. This can lead to credential theft, malware installation, or UI redress attacks, where the attacker overlays a fake login form on top of the legitimate one.
Recommendations
- Upgrade: Upgrade to a patched version of Heimdall as soon as it becomes available.
- Input Validation: Implement strict input validation for all user-supplied HTTP headers.
- Referer Validation: Do not blindly trust the `Referer` header for critical security decisions.
- Content Security Policy (CSP): Implement a strong CSP to prevent the loading of unauthorized external resources.
- Web Application Firewall (WAF): Deploy a WAF to detect and block malicious requests.
Technical Insight
The vulnerability stems from Heimdall directly using the values from the `X-Forwarded-Host` and `Referer` headers in constructing URLs without proper sanitization. By injecting a malicious domain into these headers, an attacker can force the application to redirect users to arbitrary websites or load malicious resources.
Credit to Researcher(s)
This vulnerability was discovered and reported by Juan Felipe.
References
Tags
#Heimdall #CVE-2025-50578 #HostHeaderInjection #OpenRedirect #LinuxServer #SecurityVulnerability #Phishing
Summary: Heimdall 2.6.3-ls307 is vulnerable to Host Header Injection and Open Redirect attacks due to improper validation of the `X-Forwarded-Host` and `Referer` headers. An unauthenticated attacker can manipulate these headers to redirect users to malicious sites, enabling phishing and other attacks.
CVE ID: CVE-2025-50578
Risk Analysis: Successful exploitation can lead to redirection of users to malicious sites, credential theft, malware installation, and UI redress attacks. This poses a significant risk to user data and the integrity of the application.
Recommendation: Upgrade to a patched version of Heimdall. Implement strict input validation for user-supplied HTTP headers. Utilize a Content Security Policy (CSP) and a Web Application Firewall (WAF) for added protection.
Timeline
- 2025-07-30: CVE ID assigned and vulnerability publicly disclosed.