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CVE Record

CVE-2021-36563: The CheckMK management web console (versions 1.5.0 to 2.0.0) does not sanitise user input in various parame...

The CheckMK management web console (versions 1.5.0 to 2.0.0) does not sanitise user input in various parameters of the WATO module. This allows an attacker to open a backdoor on the device with HTML content and interpreted by the browser (such as JavaScript or other client-side scripts), the XSS payload will be triggered when the user accesses some specific sections of the application. In the same sense a very dangerous potential way would be when an attacker who has the monitor role (not administrator) manages to get a stored XSS to steal the secretAutomation (for the use of the API in administrator mode) and thus be able to create another administrator user who has high privileges on the CheckMK monitoring web console. Another way is that persistent XSS allows an attacker to modify the displayed content or change the victim's information. Successful exploitation requires access to the web management interface, either with valid credentials or with a hijacked session.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-36563 is a stored cross-site scripting issue in the CheckMK management web console WATO module, reported for versions 1.5.0 to 2.0.0. A logged-in attacker, or someone using a hijacked session, could plant browser-executed content that later runs when users view affected sections.

Executive priority

Treat as high priority for affected CheckMK deployments because an authenticated stored XSS may become an administrator-impact issue. Prioritize systems where monitoring consoles are broadly reachable or where lower-privileged users can access WATO.

Technical view

The reported weakness is missing input sanitization across WATO parameters in the CheckMK web management console. Stored XSS may execute client-side script in another user's browser. The description highlights a high-impact path where a monitor-role attacker could target secretAutomation and potentially perform administrator-level API actions.

Likely exposure

Exposure is most likely where CheckMK 1.5.0 through 2.0.0 web management interfaces are reachable to users who can access WATO. Internet exposure is not established in the bundle, and successful exploitation requires valid access or a hijacked session.

Exploitation context

The CVE is not listed as KEV in the bundle, so active exploitation is not established. A public GitHub reference exists, but the supplied evidence does not prove real-world exploitation. Risk depends heavily on web console access control and user roles.

Researcher notes

The bundle lacks CVSS, CWE, and normalized affected CPE data. Analysis relies on the CVE description and listed references. Do not assume unauthenticated exploitation or active exploitation. Validate version range, WATO access, role boundaries, and vendor fix status before declaring exposure.

Mitigation direction

  • Review Checkmk Werk 12762 and 13148 for vendor-correct remediation guidance.
  • Upgrade affected CheckMK deployments according to vendor guidance if applicable.
  • Restrict management console access to trusted administrative networks and users.
  • Review WATO permissions, especially monitor-role access to sensitive workflows.
  • Investigate sessions and accounts for suspicious administrative changes.

Validation and detection

  • Inventory CheckMK management console versions and identify 1.5.0 through 2.0.0 deployments.
  • Confirm whether WATO is accessible to non-administrator users.
  • Check whether the management interface is exposed beyond trusted networks.
  • Review logs for unexpected administrator creation or permission changes.
  • Assess whether vendor fixes from referenced Werks are already applied.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/an/an/aListed
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.