Severity Rating: Important
Revision Note: V2.0 (February 10, 2015): Bulletin rereleased to announce the availability of an additional update package for Microsoft Excel Viewer (2920791) that addresses the vulnerabilities discussed in this bulletin. Note that the 2920791 update also addresses a vulnerability discussed in MS15-012, which is being released concurrently. Microsoft recommends that customers running Microsoft Excel Viewer apply the 2920791 update at their earliest convenience. See the Affected Software table for the download link.
Summary: This security update resolves two privately reported vulnerabilities in Microsoft Excel. The vulnerabilities could allow remote code execution if an attacker convinces a user to open or preview a specially crafted Microsoft Excel file in an affected version of Microsoft Office software. An attacker who successfully exploited the vulnerabilities could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Customers whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

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