How severe is CVE-2026-43984?

CVE-2026-43984 has a CVSS 3.x base score of 8.9, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.

Is CVE-2026-43984 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-43984?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-43984 have an EU (EUVD) identifier?

Yes. CVE-2026-43984 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34284.

When was CVE-2026-43984 published?

CVE-2026-43984 was published on 2026-06-04 and last updated on 2026-06-17.

CVE-2026-43984

CVE-2026-43984 is a high-severity vulnerability with a CVSS 3.x base score of 8.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: High (CVSS 3.x base score 8.9)
EPSS exploit prediction: 0% (11th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-34284
Weakness: CWE-79
Published: 2026-06-04
Last modified: 2026-06-17

Description

Tautulli is a Python based monitoring and tracking tool for Plex Media Server. Versions prior to 2.17.1 expose `log_js_errors` to any authenticated user, including guest users when guest access is enabled. The endpoint writes attacker-controlled strings directly into the main application log. The administrator-only `logFile` view then reads that log file and embeds it into an HTML response without escaping. This creates a stored cross-site scripting condition where a low-privilege guest can inject HTML or JavaScript into the log file and have it execute in an administrator's browser when the log viewer is opened. Version 2.17.1 patches the issue.

Frequently asked questions

What is CVE-2026-43984?: Tautulli is a Python based monitoring and tracking tool for Plex Media Server. Versions prior to 2.17.1 expose `log_js_errors` to any authenticated user, including guest users when guest access is enabled. The endpoint writes attacker-controlled strings directly into the main application log. The administrator-only `logFile` view then reads that log file and embeds it into an HTML response without escaping. This creates a stored cross-site scripting condition where a low-privilege guest can inject HTML or JavaScript into the log file and have it execute in an administrator's browser when the log viewer is opened. Version 2.17.1 patches the issue.
How severe is CVE-2026-43984?: CVE-2026-43984 has a CVSS 3.x base score of 8.9, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is high, integrity high, and availability low.
Is CVE-2026-43984 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (11th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-43984?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-43984 have an EU (EUVD) identifier?: Yes. CVE-2026-43984 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34284.
When was CVE-2026-43984 published?: CVE-2026-43984 was published on 2026-06-04 and last updated on 2026-06-17.

References

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