CVE-2026-53964 is a remote code execution vulnerability in Document Merge Service caused by server-side template injection during processing of XLSX templates. A maliciously crafted XLSX template can inject template expressions that are evaluated by the server during document generation, resulting in attacker-controlled code execution within the service context. Successful exploitation executes code as the document-merge-server user inside the application container.
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What an attacker gets, and what they’ve been doing with it.
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Patch, then assume compromise.
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No public exploit code observed for this vulnerability.
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No public activity observed for this vulnerability.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
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Cross-references every affected SKU, including bundled OEM variants.
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