CVE-2009-0238
CVE-2009-0238 is a security flaw in Microsoft Office, part of Microsoft Office. Opening a booby-trapped file can let an attacker run their own code through Microsoft Office. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 14 Apr 2026.[1]
Microsoft Office is in things households have, such as phones, computers, browsers and everyday apps, so the fix matters at home as much as at work. Microsoft has published a fix or advice.
Description
CISA calls it a remote code execution in Microsoft Office. In its words: “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.”[1]
The CVE record adds: “Microsoft Office Excel 2000 SP3, 2002 SP3, 2003 SP3, and 2007 SP1; Excel Viewer 2003 Gold and SP3; Excel Viewer; Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP1; and Excel in Microsoft Office 2004 and 2008 for Mac allow remote attackers to execute arbitrary code via a crafted Excel document that triggers an access attempt on an invalid object, as exploited in the wild in February 2009 by Trojan.Mdropper.AC.”[2]
The underlying weakness is code injection (CWE-94), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Microsoft’s advisory has them[3]. CISA names the product as Microsoft Office.
Every device with Microsoft Office needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 14 Apr 2026, 6,257 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 28 Apr 2026 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 43%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Microsoft has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Update Microsoft Office now.On Windows: Settings, Windows Update, Check for updates, then restart. Office updates come the same way, or from any Office app: File, Account, Update Options. Then turn on automatic updates, so the next fix arrives on its own.
- If there’s no update, stop using it.CISA’s advice when a flaw being used in attacks has no fix is to stop using the product until it does.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 8.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 43%.[4] |
See also
Other Microsoft Office flaws
- CVE-2026-21514: word reliance on untrusted inputs in a security decision ·
- CVE-2026-21509: security feature bypass ·
- CVE-2009-0556: powerPoint code injection ·
- CVE-2007-0671: excel remote code execution ·
- CVE-2023-23397: outlook privilege escalation ·
- CVE-2023-21715: publisher security feature bypass ·
Other Microsoft flaws
- CVE-2026-96951, Microsoft Windows: command injection ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
- CVE-2026-85880, Microsoft Windows: heap-based buffer overflow ·
- CVE-2026-81963, Microsoft Windows: link following ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
Other code injection flaws
- CVE-2026-0322, Palo Alto Networks PAN-OS: code injection ·
- CVE-2026-60004, Gitea: code injection ·
- CVE-2026-72530, TrueConf Server: code injection ·
- CVE-2025-62593, Ray-Project Ray: code injection ·
- CVE-2026-9198, IBM Langflow: code injection ·
Added the same day
- CVE-2026-32201, Microsoft SharePoint Server: improper input validation ·
Every Microsoft flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Microsoft Office Remote Code Execution”. Known Exploited Vulnerabilities Catalog, added 14 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2009-0238 Detail”. National Vulnerability Database, published 25 Feb 2009.
- ^ Microsoft. Advisories and fixes: learn.microsoft.com, docs.microsoft.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.429, percentile 98.7, 31 Oct 2026.
- CVE Program. “CVE-2009-0238”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.