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Microsoft Office Click-to-Run Elevation of Privilege Vulnerability
CVE-2026-35436 is an elevation-of-privilege vulnerability in Microsoft Office Click-to-Run caused by insufficient granularity of access control in shared Click-to-Run infrastructure. The flaw affects Click-to-Run-based Microsoft Office deployments and can be exploited by a low-privileged local attacker without user interaction. Successful exploitation allows an attacker operating within the Office Click-to-Run AppContainer to escape that sandbox and cross the component security boundary, resulting in SYSTEM-level privileges on the host. The issue is local-only and is not exploitable through the Preview Pane.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation allows a low-privileged local attacker to break out of the Office Click-to-Run AppContainer sandbox and elevate privileges to SYSTEM. Because the scope is changed, compromise extends beyond the vulnerable component’s original security boundary. This can result in full compromise of the affected host, including high-impact effects on confidentiality, integrity, and availability.
If you can’t patch tonight, do this now.
No separate vendor workaround or hotfix outside the official fix is currently available. Mitigation is limited to promptly applying the vendor-provided Office Click-to-Run updates and validating that affected systems have moved to remediated build versions. Reducing opportunities for local code execution by low-privileged users can also reduce exposure until patching is complete.
Patch, then assume compromise.
Apply Microsoft's May 12, 2026 security updates for affected Microsoft Office Click-to-Run products. Remediation is delivered through updated Office Click-to-Run build versions rather than a standalone KB patch. Affected organizations should update supported channels and verify that endpoints are running patched Office builds. Traditional MSI-based Office installations are not affected by this vulnerability.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
5 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.