CVE-2026-25885CWE-285CWE-306

PolarLearn allows Unauthenticated WebSocket access allows subscribing to and posting in arbitrary group chats

Critical · published February 9, 2026

CVSS v4.0
10.0
EPSS
0%
Percentile
39.7
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
10.0 · CRITICAL
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
EPSS
0.00470 · 39.7th percentile
Weaknesses
CWE-285 · Improper Authorization; CWE-306 · Missing Authentication for Critical Function
Published
2026-02-09T21:15Z
EPSS history
Timeline
  • 09 FEB 21:15Z
    PolarLearn allows Unauthenticated WebSocket access allows subscribing to and posting in arbitrary group chats
    cvelistv5