VulniosVulnios
All Threat Alerts
criticalCVE Alert
CVE-2026-35031

Critical Vulnerability: CVE-2026-35031

Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain a vulnerability chain in the subtitle upload endpoint (POST /Videos/{itemId}/Subtitles), where the Format field is not validated, allowing path traversal via the file extension and enabling arbitrary file write. This arbitrary file write can be chained into arbitrary file read via .strm files, database extraction, admin privilege escalation, and ultimately remote code execution as root via ld.so.preload. Explo

Tuesday, April 14, 2026Vulnios Threat Intelligence
Share:

Executive Summary

Jellyfin is an open source self hosted media server. Versions prior to 10.11.7 contain a vulnerability chain in the subtitle upload endpoint (POST /Videos/{itemId}/Subtitles), where the Format field is not validated, allowing path traversal via the file extension and enabling arbitrary file write. This arbitrary file write can be chained into arbitrary file read via .strm files, database extraction, admin privilege escalation, and ultimately remote code execution as root via ld.so.preload. Exploitation requires an administrator account or a user that has been explicitly granted the "Upload Subtitles" permission. This issue has been fixed in version 10.11.7. If users are unable to upgrade immediately, they can grant non-administrator users Subtitle upload permissions to reduce attack surface.

Why It Matters

CVE-2026-35031 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.9/10

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2026-35031.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2026-35031 and similar vulnerabilities.

    References & Sources

  • https://github.com/jellyfin/jellyfin/releases/tag/v10.11.7
  • https://github.com/jellyfin/jellyfin/security/advisories/GHSA-j2hf-x4q5-47j3

    • AI Security Advisor

    Powered by Gemini

    Get AI-powered security recommendations tailored to this specific threat — including risk assessment, detection guidance, MITRE ATT&CK mapping, and actionable remediation steps.

    Sources

    criticalrceprivesc

    Protect Your Organization

    Monitor CVEs, scan for vulnerabilities, and get real-time threat alerts — all in one platform.

    Get Started FreeFree Security ScanOSINT Dashboard

    Get instant alerts on Telegram

    Join our public channel for real-time critical CVE alerts.

    Follow @vulnios