CVE-2026-56843 — CRITICAL (9.9)

Vulnerability Description

Incorrect authorization in the XML-RPC API of WebPros Plesk before 18.0.78.4 allows a low-privileged authenticated customer to look up domains they do not own, because ownership is enforced only for certain lookup filters and schema validation is bypassed for legacy protocol versions. This results in cross-tenant disclosure of other tenants' FTP credentials stored in cleartext, which can be leveraged to execute code as another tenant's system user.

CVSS Score

9.9

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-522

References

https://support.plesk.com/hc/en-us/articles/41178305151255-Vulnerability-in-Ples

FAQ

What is CVE-2026-56843?

CVE-2026-56843 is a vulnerability with a CVSS score of 9.9 (CRITICAL). Incorrect authorization in the XML-RPC API of WebPros Plesk before 18.0.78.4 allows a low-privileged authenticated customer to look up domains they do not own, because ownership is enforced only for c...

How severe is CVE-2026-56843?

CVE-2026-56843 has been rated CRITICAL with a CVSS base score of 9.9/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-56843?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.