CVE-2026-55044 in Office
Summary
by MITRE • 07/14/2026
Out-of-bounds read in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical memory safety issue within Microsoft Office Excel that enables remote code execution through crafted malicious files. The out-of-bounds read occurs when the application processes specially constructed spreadsheet elements without proper validation of array indices or buffer boundaries, allowing attackers to manipulate memory access patterns beyond allocated data structures. This flaw falls under the common weakness enumeration CWE-125 which specifically addresses out-of-bounds read conditions that can lead to arbitrary code execution. The vulnerability demonstrates characteristics consistent with attack techniques described in the MITRE ATT&CK framework under T1059 for command and script injection, where an attacker leverages software flaws to execute malicious payloads within the target environment.
The technical implementation of this vulnerability involves Excel's parsing engine encountering malformed data structures within spreadsheet files that trigger memory access violations. When processing certain cell formats, formulas, or embedded objects, the application fails to validate input parameters against predetermined buffer limits, enabling attackers to craft malicious .xlsx files that exploit this condition. The flaw typically manifests during the rendering or calculation phases of spreadsheet processing, where the application attempts to read data from memory locations that either do not exist or contain sensitive information that could be manipulated for exploitation purposes. Such vulnerabilities often stem from insufficient bounds checking mechanisms in legacy code components that handle complex spreadsheet formatting and data structures.
The operational impact of this vulnerability extends beyond simple code execution capabilities as it provides attackers with a persistent foothold within targeted environments. Once successfully exploited, adversaries can execute arbitrary commands with the privileges of the affected user, potentially leading to full system compromise through privilege escalation techniques or lateral movement within network infrastructures. The attack vector typically involves social engineering campaigns where users unknowingly open malicious Excel files delivered via email attachments or compromised websites. This vulnerability is particularly dangerous in enterprise environments where Office applications are widely deployed and users frequently interact with external documents, creating multiple potential entry points for exploitation.
Mitigation strategies should prioritize immediate patch deployment from Microsoft security updates that address the specific memory validation issues within Excel's parsing components. Organizations must implement comprehensive email filtering solutions to block suspicious attachments and maintain strict software update policies that ensure all Office installations remain current with security patches. Network-based defenses including web application firewalls and sandboxing technologies can provide additional layers of protection by analyzing and quarantining potentially malicious spreadsheet content before it reaches end-user systems. Security teams should also establish monitoring protocols for unusual Excel process behavior or unexpected memory access patterns that could indicate exploitation attempts, while maintaining regular vulnerability assessments to identify similar weaknesses in other Microsoft Office components that may present comparable risks.