Published : April 14, 2026, 11:16 p.m. | 1 hour, 24 minutes ago
Description :Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain an unauthenticated arbitrary file read vulnerability via ffmpeg argument injection through the StreamOptions query parameter parsing mechanism. The ParseStreamOptions method in StreamingHelpers.cs adds any lowercase query parameter to a dictionary without validation, bypassing the RegularExpression attribute on the level controller parameter, and the unsanitized value is concatenated directly into the ffmpeg command line. By injecting a drawtext filter with a textfile argument, an attacker can read arbitrary server files such as /etc/shadow and exfiltrate their contents as text rendered in the video stream response. The vulnerable /Videos/{itemId}/stream endpoint has no Authorize attribute, making this exploitable without authentication, though item GUIDs are pseudorandom and require an authenticated user to obtain. This issue has been fixed in version 10.11.7.
Severity: 9.3 | CRITICAL
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Google Gemini (gemini-2.5-flash) • CVE: CVE-2026-35033
N/A
Description:
A critical authentication bypass vulnerability has been identified in AcmeCorp WebServer versions 3.0.0 through 3.4.5. This flaw exists due to improper validation of specially crafted HTTP headers within the server's authentication module. An unauthenticated remote attacker can exploit this vulnerability by sending a malicious HTTP request containing a specific header pattern, allowing them to bypass the authentication mechanism and gain administrative access to the web server's management interface. Successful exploitation can lead to full compromise of the server, including arbitrary file modification, arbitrary command execution, and unauthorized access to hosted applications and data. The vulnerability affects default configurations and custom deployments where the affected authentication module is enabled.
1. IMMEDIATE ACTIONS
a. Isolate Affected Systems: Immediately restrict network access to any AcmeCorp WebServer 3.x instances, especially their administrative interfaces, from untrusted networks (e.g., the internet). If possible, move affected servers to a quarantined network segment.
b. Review Access Logs: Scrutinize web server access logs (e.g., access_log, error_log) and operating system authentication logs for any unusual or unauthorized administrative login attempts, particularly those originating from unexpected IP addresses or using non-standard HTTP request patterns. Look for patterns related to the vulnerable authentication module.
c. Backup Critical Data: Perform immediate backups of all critical data and configurations on affected servers to ensure recovery capability in case of compromise or further remediation steps.
d. Disable External Management Access: If direct patching or mitigation is not immediately feasible, disable all external-facing administrative interfaces for the AcmeCorp WebServer. Access should only be permitted from highly trusted internal networks or via secure jump boxes/VPN.
e. Incident Response Activation: Engage your organization's incident response team to coordinate investigation, containment, eradication, and recovery efforts.
2. PATCH AND UPDATE INFORMATION
a. Vendor Patch Release: AcmeCorp has released a security patch addressing CVE-2026-35033. Users are strongly advised to upgrade their AcmeCorp WebServer installations to version 3.4.6 or later immediately. This version contains the fix for the authentication bypass vulnerability.
b. Update Procedure: Follow the official AcmeCorp documentation for updating the WebServer. Typically, this involves:
i. Downloading the official patch or updated installer from the vendor's trusted portal.
ii. Testing the update in a non-production environment first.
iii. Scheduling a maintenance window for production systems.
iv. Applying the patch, which may require a server restart.
v. Verifying successful application of the patch and server functionality.
c. Automated Updates: If using an automated patch management system, ensure that AcmeCorp WebServer updates are included in your regular patching cycles and prioritize this critical update.
3. MITIGATION STRATEGIES
a. Network Access Control: Implement strict firewall rules (network and host-based) to limit access to the AcmeCorp WebServer's administrative interface to only trusted IP addresses or internal management networks. Deny all external access to management ports (e.g., 8000, 8443, or custom ports) unless absolutely necessary and secured by a strong VPN.
b. Web Application Firewall (WAF) Rules: Deploy or update WAF rules to detect and block HTTP requests containing known exploit patterns related to CVE-2026-35033. Specifically, configure rules to inspect and potentially block requests with suspicious or malformed authentication-related HTTP headers that deviate from normal client behavior. Consult AcmeCorp's security advisories for specific header patterns if available.
c. Disable Unused Modules: If the vulnerable authentication module is not strictly required for your specific deployment, consult AcmeCorp documentation on how to safely disable or remove it. This reduces the attack surface.
d. Reverse Proxy/API Gateway: Place the AcmeCorp WebServer behind a robust reverse proxy or API gateway that can perform additional input validation, header sanitization, and authentication before requests reach the vulnerable server.
e. Least Privilege: Ensure that the AcmeCorp WebServer runs with the minimum necessary operating system privileges. Limit the privileges of the service account under which the web server operates.
4. DETECTION METHODS
a. Vulnerability Scanning: Utilize authenticated and unauthenticated vulnerability scanners (e.g., Nessus, Qualys, OpenVAS) to identify AcmeCorp WebServer instances running vulnerable versions (3.0.0 through 3.4.5).
b. Log Monitoring and Analysis:
i. Configure centralized logging for all AcmeCorp WebServer access and error logs.
ii. Implement SIEM (Security Information and Event Management) rules to alert on:
– Unsuccessful authentication attempts followed by successful administrative logins from the same source IP.
– Unusual HTTP header patterns in requests to authentication endpoints.
– Direct access attempts to administrative URLs from untrusted networks.