CVE-2026-97381 (CVSS 9.9)

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.

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CVSS v3.1 Score

9.9

CRITICAL

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

EPSS — Exploit Prediction

0.0021

Probability of exploitation

0.11%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-346 CWE-346

CWE-393 CWE-393

References

Other References

https://github.com/LegacyUpdate/LegacyUpdate/commit/7d62f0bfaa770d74cd6e2cb0bac9c1907df48033 https://github.com/LegacyUpdate/LegacyUpdate/commit/ae1c46c97f39a55a1937784d9f9beb30aa9147fd https://github.com/LegacyUpdate/LegacyUpdate/releases/tag/v1.13.2.0 https://github.com/LegacyUpdate/LegacyUpdate/security/advisories/GHSA-f4g7-4gmx-jfgf https://legacyupdate.net/news/2026/07/21/legacy-update-1-13-2

Frequently Asked Questions

What is CVE-2026-97381? +

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. It has a CVSS v3.1 base score of 9.9 (CRITICAL).

How severe is CVE-2026-97381? +

CVE-2026-97381 has a CVSS v3.1 score of 9.9 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0021, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-97381? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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