CVE-2009-0238 Microsoft Office: command or code injection
In plain words: The program treats text it receives as instructions instead of plain data. The attacker can run commands on the machine — often the whole device is taken over.
Confirmed exploited by CISA on · US federal patch deadline Apr 28, 2026
What to do
- Install Microsoft's security update for Office. If no update exists, follow the vendor's workaround or stop using the product until one ships.
- Turn on automatic updates for the operating system and for Office, PDF and archive apps.
- Be careful with unexpected attachments — documents, .zip/.rar files and shortcuts are common bait.
- Use a normal (non-admin) account day to day and keep built-in protection like Microsoft Defender on.
Who is affected
Could reach you. This one is aimed at devices or apps of the kind people own.
What's at risk: Your files, saved passwords and accounts. Many of these let a program that is already running gain full administrator control.
The details
- Official name
- Microsoft Office Remote Code Execution
- Product
- Microsoft Office
- CISA description
- Microsoft Office Excel contains a remote code execution vulnerability that could allow an attacker to take complete control of an affected system if a user opens a specially crafted Excel file that includes a malformed object.
- Type of flaw
- Command or code injection (CWE-94)
- Confirmed exploited
- Apr 14, 2026
- US federal patch deadline
- Apr 28, 2026
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Answering about CVE-2009-0238 ·
Questions about CVE-2009-0238
Is CVE-2009-0238 being exploited?
Yes. CISA added CVE-2009-0238 to its Known Exploited Vulnerabilities catalog on Apr 14, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2009-0238?
Install Microsoft's security update for Office. If no update exists, follow the vendor's workaround or stop using the product until one ships. Turn on automatic updates for the operating system and for Office, PDF and archive apps.
Am I affected by CVE-2009-0238?
Only if you use Microsoft Office. This one is aimed at devices or apps of the kind people own.