Description
Incorrect authorization in the User Messages dashboard widget in Checkmk <2.5.0p5 causes the message-fetching endpoints to return the dashboard creator's messages rather than the viewer's, allowing an attacker who knows a valid public dashboard share token to read the issuer's personal messages by sending requests to the underlying endpoint, even without a User Messages widget present.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Checkmk | Checkmk | 2.5.0 – < 2.5.0p5 | 2.5.0p5 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | check-mk | No fix yet | — |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | check-mk | No fix yet | — |
Advisories 1
- WID-SEC-2026-1817 Checkmk: Mehrere Schwachstellen ermöglichen Cross-Site Scripting BSI CERT-Bund (WID) · Jun 8, 2026
References
- https://checkmk.com/werk/19815 vendor-advisory