CVE-2026-71555

MEDIUM 4.1

PILOS: Reverse tabnabbing in room description

CVSS Score

4.1

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-1022
Vendor	thm-health
Product	pilos
Published	Aug 6, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

None

Integrity

Low

Availability

None

Affected Versions

THM-Health / PILOS

>= 2.1.0, < 4.14.1

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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