critical CVSS 10

CVE-2026-28505·Python vulnerability

Tautulli is a Python based monitoring and tracking tool for Plex Media Server. Prior to version 2.17.0, the str_eval() function in notification_handler.py implements a sandboxed eval() for notification text templates. The sandbox attempts to restrict callable names by inspecting code.co_names of the compiled code object. However, co_names only contains names from the outer code object. When a lambda expression is used, it creates a nested code object whose attribute accesses are stored in code.co_consts, NOT in code.co_names. The sandbox never inspects nested code objects. This issue has been patched in version 2.17.0.

Severity
critical
Software
Python
Fixed in
2.17.0
Published
2026-03-30

Affected versions

Until: 2.17.0

Fixed in: 2.17.0

How to fix this CVE

Upgrade Tautulli to version 2.17.0 or later to patch a critical sandbox escape vulnerability in the notification template engine. The flaw allows attackers to bypass code execution restrictions by embedding lambda expressions in notification text templates. Immediate patching is strongly recommended given the CVSS 10.0 rating and complete system compromise potential.

sudo dnf update tautulli

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'tautulli --version' or check /path/to/tautulli/version.txt to determine the installed Tautulli version; versions prior to 2.17.0 are vulnerable
  2. Verify if Tautulli has notification templates enabled by checking the config.ini file for 'notification_handler' and custom template settings
  3. Search Tautulli logs (/var/log/tautulli/tautulli.log or configured log path) for errors containing 'str_eval', 'lambda', or 'SyntaxError' which may indicate exploitation attempts
  4. Confirm the patch by verifying 'tautulli --version' returns 2.17.0 or higher, and review notification_handler.py in the Tautulli installation directory for the nested code object inspection fix

FAQ

What is CVE-2026-28505?

CVE-2026-28505 is a critical code execution vulnerability in Tautulli's notification template system where the sandbox protection mechanism fails to inspect nested code objects created by lambda expressions, allowing attackers to execute arbitrary Python code.

Is CVE-2026-28505 being actively exploited?

No, this vulnerability is not currently listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are available, though the critical CVSS score warrants immediate patching as a precaution.

What versions of Tautulli are affected by CVE-2026-28505?

All Tautulli versions prior to 2.17.0 are affected; version 2.17.0 and later contain the fix.

How do I check if my server is vulnerable to CVE-2026-28505?

Run 'tautulli --version' and compare the output to 2.17.0; if your version is lower, your installation is vulnerable. Also verify notification templates are active in your Tautulli configuration.

Does Defensia detect CVE-2026-28505?

Yes — Defensia's CVE advisory scanner compares installed Tautulli versions against the NVD database. If Tautulli is installed on a monitored server, CVE-2026-28505 will appear in your dashboard with remediation steps.

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References

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