Microsoft has confirmed that the September 8, 2026 Excel security update KB5002914 can silently break copy and paste in Excel 2016, 2019, 2021, and 2024.

Microsoft added the defect to the update’s known issues after Patch Tuesday users reported that paste, autofill, and formula dragging failed with no error.

Microsoft’s advisory says the paste operation might fail silently. A user copies a cell or range, then pastes, but the source remains selected, and the destination never changes.

No beep or error message appears, so finance and operations staff may believe data transferred when the sheet is still empty. That lack of feedback is what makes the bug so easy to miss during routine spreadsheet work.

Reports on Reddit and Microsoft Q&A described the same behavior after the September 9 install wave, including broken drag-fill, with some teams already fully patched before anyone noticed.

Typing a few values, copying them, and pasting nearby is enough to confirm the bug. KB5002914 is a security release for Excel 2016 that addresses remote code execution

and information disclosure, tying to September CVEs such as CVE-2026-81399, CVE-2026-81390, and CVE-2026-81954. The standalone Microsoft Download Center packages apply only to MSI-based Office 2016, not Click-to-Run editions such as Microsoft 365 Home.

The update is also available from Microsoft Update and the Microsoft Update Catalog, and it replaces security update 5002886.

That mix of serious Excel flaws and a core productivity break is why administrators are now stuck between keeping the patch and keeping spreadsheets usable.

The public KB is written for Excel 2016, yet Microsoft’s known-issue note names Excel 2024, 2021, 2019, and 2016. Field reports also cover MSI and Click-to-Run installs and Office LTSC Standard 2021, pointing to a broader September Office servicing problem rather than a single 2016 MSI package.

Microsoft says it is researching the issue and will post more information when it becomes available, as detailed in the support advisory published by Microsoft. No hotfix date has been published as of September 15, 2026.

Until an official repair ships, the only widely confirmed recovery is to uninstall or roll back KB5002914. MSI customers say removal restores paste, while Click-to-Run sites have used XML or Group Policy to revert the Office build. Both moves drop the month’s Excel security fixes.

Replacing the updated excel.exe with an older binary is an unsupported folk workaround and can leave mixed files that create new security and stability gaps.

Teams that must restore Excel should document the exception, treat untrusted workbooks as high risk, and watch Microsoft’s KB5002914 advisory for an out-of-band fix.

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