CVE-2009-0556 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 Jan 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 PowerPoint Code Injection Vulnerability
- Product
- Microsoft Office
- CISA description
- Microsoft Office PowerPoint contains a code injection vulnerability that allows remote attackers to execute arbitrary code via a PowerPoint file with an OutlineTextRefAtom containing an invalid index value that triggers memory corruption.
- Type of flaw
- Command or code injection (CWE-94)
- Confirmed exploited
- Jan 7, 2026
- US federal patch deadline
- Jan 28, 2026
Ask Cleus about it
Ask about a vulnerability, an update, a weird message, or the news. Plain-word answers, free, no account.
Answering about CVE-2009-0556 ·
Questions about CVE-2009-0556
Is CVE-2009-0556 being exploited?
Yes. CISA added CVE-2009-0556 to its Known Exploited Vulnerabilities catalog on Jan 7, 2026, which means there is reliable evidence of real-world attacks.
How do I fix CVE-2009-0556?
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-2009-0556?
Only if you use Microsoft Office. This one is aimed at devices or apps of the kind people own.