Vulnerability · Published Aug 6, 2026 · Assigned by GitHub_M

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

Medium 4.1

In plain English

A medium-severity security flaw in PILOS from THM-Health. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 3.1)4.1Medium

Exploit odds (30 days)0.3%top 78.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
THM-Health	PILOS	>= 2.1.0, < 4.14.1

Weakness: CWE-1022 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:N

References

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