# CVE-2026-43984: Tautulli has stored XSS in logFile via guest-controlled log_js_errors input

> A low-privilege guest can inject JavaScript into logs that executes in an administrator's browser, enabling session hijacking or malicious actions.

- **Severity:** High 8.9 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 4 Jun 2026
- **Updated:** 4 Jun 2026
- **Also known as:** GHSA-f4j7-pjwc-4jrr

## What is CVE-2026-43984?

CVE-2026-43984 is a high-severity cross-site scripting vulnerability in Tautulli, published on 4 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-43984?


## How do I fix CVE-2026-43984?

No fix has been published for CVE-2026-43984 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43984 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43984 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43984 and fix it if it is affected.

What it is: CVE-2026-43984 is a high-severity cross-site scripting vulnerability in Tautulli, published on 4 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43984 exists.

Affected product: Tautulli. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-43984/ (Markdown: https://insights.sbomify.com/CVE-2026-43984/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43984
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43984
- OSV: https://osv.dev/vulnerability/CVE-2026-43984

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-43984/
Summaries are generated and may contain mistakes; the official description above is the record.