CVE-2026-25885: Polarlearn

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

PolarLearn is a free and open-source learning program. In 0-PRERELEASE-16 and earlier, the group chat WebSocket at wss://polarlearn.nl/api/v1/ws can be used without logging in. An unauthenticated client can subscribe to any group chat by providing a group UUID, and can also send messages to any group. The server accepts the message and stores it in the group’s chatContent, so this is not just a visual spam issue.

Affected products

• Polarlearn Polarlearn: affected versions not specified

Published 2026-02-09. Last modified 2026-06-17.