# CVE-2026-33403: Pi-hole has a Reflected XSS / HTML injection in taillog.js

> An unauthenticated attacker can inject HTML via a crafted URL to steal credentials from the Pi-hole admin interface due to improper output encoding.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 6 Apr 2026
- **Updated:** 6 Apr 2026
- **Also known as:** GHSA-7xqw-r9pr-qv59

## What is CVE-2026-33403?

CVE-2026-33403 is a medium-severity cross-site scripting vulnerability in pi-hole web, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Pi-hole Admin Interface is a web interface for managing Pi-hole, a network-level ad and internet tracker blocking application. From 6.0 to before 6.5, a reflected DOM-based XSS vulnerability in taillog.js allows an unauthenticated attacker to inject arbitrary HTML into the Pi-hole admin interface by crafting a malicious URL. The file query parameter is interpolated into an innerHTML assignment without escaping. Because the Content-Security-Policy is missing the form-action directive, injected <form> elements can exfiltrate credentials to an external origin. This vulnerability is fixed in 6.5.

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

## Which versions are affected by CVE-2026-33403?

It affects 1 product.


Products: Pi-Hole Web Interface.

## How do I fix CVE-2026-33403?

No fix has been published for CVE-2026-33403 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-33403 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33403 exists.

## Other vulnerabilities in pi-hole web

- [CVE-2026-33765](https://insights.sbomify.com/CVE-2026-33765/): Pi-hole Web Interface has a Command Injection Vulnerability (high 8.9)
- [CVE-2023-23614](https://insights.sbomify.com/CVE-2023-23614/): Improper session handling of "Remember me for 7 days" functionality (high 8.8)
- [CVE-2025-59151](https://insights.sbomify.com/CVE-2025-59151/): Pi-hole Admin Interface vulnerable to HTTP response header injection via CRLF injection (high 8.2)
- [CVE-2021-3706](https://insights.sbomify.com/CVE-2021-3706/): Sensitive Cookie Without 'HttpOnly' Flag in pi-hole/adminlte (high 7.4)
- [CVE-2021-41175](https://insights.sbomify.com/CVE-2021-41175/): Stored XSS in Client Groups Management (Authenticated) (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33403 and fix it if it is affected.

What it is: CVE-2026-33403 is a medium-severity cross-site scripting vulnerability in pi-hole web, published on 6 Apr 2026. An attacker can exploit it over the internet without logging in, 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-2026-33403 exists.

Affected product: pi-hole web. 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-2026-33403/ (Markdown: https://insights.sbomify.com/CVE-2026-33403/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33403
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33403
- OSV: https://osv.dev/vulnerability/CVE-2026-33403

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33403/
Summaries are generated and may contain mistakes; the official description above is the record.