Microsoft has acknowledged that the September 8, 2026, Excel security update KB5002914 can silently break copy and paste functionality in Excel 2016, 2019, 2021, and 2024. Following Patch Tuesday reports, Microsoft included the defect in the update's known issues. No beep or error message appears, leading to finance and operations staff believing data was transferred when the sheet was empty.
This combination of serious Excel vulnerabilities and a core productivity break has left administrators in a difficult position, caught between applying the patch and maintaining spreadsheet functionality. Field reports also cover MSI and Click-to-Run installations, as well as Office LTSC Standard 2021, indicating a broader September Office servicing issue rather than a specific 2016 MSI package.
MSI customers report that removal of the Office build restores paste functionality, while Click-to-Run sites have used XML or Group Policy to revert the Office version. Both methods eliminate the month's Excel security updates, and replacing the updated excel.exe with an older binary is an unsupported folk remedy that can leave behind mixed files, creating new security and stability issues. Teams tasked with restoring Excel should document exceptions, treat untrusted workbooks as high risk, and monitor Microsoft’s KB5002914 advisory for an out-of-band fix.
