# What is CVE-2011-0656?

> CVE-2011-0656 is a critical-severity flaw (CVSS 9.3) in Office from Microsoft, published on 13 April 2011. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 30%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2011-0656

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 55 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** Critical (CVSS 9.3 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 30% (latest exploit-likelihood forecast)
- **Published:** 13 April 2011
- **Record last updated:** 16 June 2026
- **Main product:** Office from Microsoft
- **Affected products:** 7

## What is CVE-2011-0656? In plain terms

It can be attacked from anywhere on the internet without logging in. If it works, the attacker can read data, change data and take it offline.

### The official description

Microsoft PowerPoint 2002 SP3, 2003 SP3, 2007 SP2, and 2010; Office 2004, 2008, and 2011 for Mac; Open XML File Format Converter for Mac; Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats SP2; PowerPoint Viewer; PowerPoint Viewer 2007 SP2; and PowerPoint Web App do not properly validate PersistDirectoryEntry records in PowerPoint documents, which allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a Slide with a malformed record, which triggers an exception and later use of an unspecified method, aka "Persist Directory RCE Vulnerability."

### What kind of flaw is it?

- CWE-20: Improper Input Validation

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Some conditions needed
- Login needed first: No login needed
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `AV:N/AC:M/Au:N/C:C/I:C/A:C`

## Is CVE-2011-0656 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 30%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 30%, 30%, 30%, 30%, 30%, 30%, 30%.

### Timeline

- 13 April 2011: Published
- 16 June 2026: Exploit likelihood fell
- 16 June 2026: Record last updated

### How Precursor Intelligence ranks it

CVE-2011-0656 scores **55 out of 100 (Medium)**, with the action "Plan remediation".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2011-0656?

The published record lists 7 products.

- [Office](https://www.precursorintelligence.com/product/microsoft/office) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2004, 2008, 2011
- [Powerpoint](https://www.precursorintelligence.com/product/microsoft/powerpoint) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2002-sp3, 2003-sp3, 2007-sp2, 2010
- [Office Compatibility Pack](https://www.precursorintelligence.com/product/microsoft/office_compatibility_pack) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2007-sp2
- [Office Powerpoint Viewer](https://www.precursorintelligence.com/product/microsoft/office_powerpoint_viewer) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): all versions
- [Open XML File Format Converter](https://www.precursorintelligence.com/product/microsoft/open_xml_file_format_converter) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): all versions
- [Powerpoint Viewer](https://www.precursorintelligence.com/product/microsoft/powerpoint_viewer) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2007-sp2
- [Powerpoint Web App](https://www.precursorintelligence.com/product/microsoft/powerpoint_web_app) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): all versions

## How do I fix CVE-2011-0656?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [vupen.com](http://www.vupen.com/english/advisories/2011/0941) (Vendor advisory)
- [osvdb.org](http://osvdb.org/71770)
- [securityfocus.com](http://www.securityfocus.com/archive/1/517482/100/0/threaded)
- [securityfocus.com](http://www.securityfocus.com/bid/47251)
- [securitytracker.com](http://www.securitytracker.com/id?1025340)
- [us-cert.gov](http://www.us-cert.gov/cas/techalerts/TA11-102A.html) (Government resource)
- [zerodayinitiative.com](http://www.zerodayinitiative.com/advisories/ZDI-11-125)
- [docs.microsoft.com](https://docs.microsoft.com/en-us/security-updates/securitybulletins/2011/ms11-022)
- [oval.cisecurity.org](https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A11761)

## Questions

### What is CVE-2011-0656?

CVE-2011-0656 is a critical-severity flaw in Office from Microsoft, published on 13 April 2011. It can be attacked from anywhere on the internet without logging in. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2011-0656?

It scores 9.3 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2011-0656 is 55 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2011-0656 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 30%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2011-0656 affect?

For Office from Microsoft: 2004, 2008, 2011. The record lists 7 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2011-0656?

Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2011-0656 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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