by Kastro
Paper/Archive/CVE-2026-25885

CVE-2026-25885

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

EPSS 0.3%CVSS 10.0
critical.is priorityof 100
35
CVSS 10.0 (CNA)10.0 / 10 × 3030.0Not in CISA KEV+300.0EPSS percentile 26.5.265 × 205.3No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

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

ProductAffectedFixed inSource
PolarLearn< 0-PRERELEASE-16–CNA

Scores by source

GitHub_M (CNA)10.0CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: partial

References

refgithub.com/polarnl/PolarLearn/security/advisories/GHSA-gvjm-5pw7-6c8crefgithub.com/polarnl/PolarLearn/commit/3ba588fda0d3f8e238483a20772719f27e52e79f