CVE-2026-71555 PILOS: Reverse tabnabbing in room description
Attackers can exploit reverse tabnabbing to redirect authenticated PILOS users to phishing pages by manipulating the original tab via window.opener.
- 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
- None listed
What is CVE-2026-71555?
CVE-2026-71555 is a medium-severity vulnerability in THM-Health PILOS, published on 6 Aug 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
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.
Weakness: CWE-1022
Which versions are affected by CVE-2026-71555?
How do I fix CVE-2026-71555?
No fix has been published for CVE-2026-71555 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-71555 being exploited?
There is no known exploitation of CVE-2026-71555 in the wild and no public exploit code.
Sources
Also known as GHSA-j4wr-p8gh-xrw5.