Description
Legacy Update is a tool for activating and installing updates on legacy Windows PCs. Legacy Update 1.12.0 through 1.13.1 contains an origin validation error in the IsPermitted method of its ActiveX control. After successfully reading the hosting document's hostname, a hostname that is not on the permitted list falls through without setting E_ACCESSDENIED, causing IsPermitted to return S_OK. An attacker who induces a user to visit a malicious webpage in Internet Explorer can invoke the control to enumerate update and system information, install updates without consent, display dialogs, or restart the computer when a reboot is pending. This issue was fixed in Legacy Update 1.13.2.
References5
- github.com/LegacyUpdate/LegacyUpdate/commit/7d62f0bfaa770d74cd6…
- github.com/LegacyUpdate/LegacyUpdate/commit/ae1c46c97f39a55a193…
- github.com/LegacyUpdate/LegacyUpdate/releases/tag/v1.13.2.0
- github.com/LegacyUpdate/LegacyUpdate/security/advisories/GHSA-f…
- legacyupdate.net/news/2026/07/21/legacy-update-1-13-2
Metrics
- CVSS 3.1
-
9.9
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 12 · as of 11 November 2026
- CWE
- CWE-346CWE-393
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.