# What is CVE-2009-1123?

> CVE-2009-1123 is a high-severity flaw (CVSS 7.8) in Windows 2000 from Microsoft, published on 10 June 2009. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 4.9%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2009-1123

## At a glance

- **Verdict:** Fix this now. Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
- **Precursor Intelligence risk score:** 74 out of 100 (High); action: Emergency patch. Kept up to date as the evidence changes.
- **Severity:** High (CVSS 7.8 out of 10)
- **Known to be exploited:** Yes, it is on the government list of flaws known to be exploited
- **Chance of use in the next 30 days:** 4.9% (latest exploit-likelihood forecast)
- **Published:** 10 June 2009
- **Record last updated:** 16 June 2026
- **Main product:** Windows 2000 from Microsoft
- **Affected products:** 5

## What is CVE-2009-1123? In plain terms

An attacker has to be already on the device without logging in, but a person has to take an action first. If it works, the attacker can read data, change data and take it offline.

### The official description

The kernel in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 SP2 does not properly validate changes to unspecified kernel objects, which allows local users to gain privileges via a crafted application, aka "Windows Kernel Desktop Vulnerability."

### What kind of flaw is it?

- Unknown: Unknown

### How an attack on it works

- Where an attacker can be: Already on the device
- How hard it is to pull off: Easy: no special conditions
- Login needed first: No login needed
- Does someone have to click: Yes, a person has to take an action
- What an attacker gets: Can read data, change data and take it offline

Severity vector: `CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`

## Is CVE-2009-1123 being exploited? Yes

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 4.9%.

Exploit likelihood over the last 7 days: 4.9%, 4.9%, 4.9%, 4.9%, 4.9%, 4.9%, 4.9%.

### Timeline

- 10 June 2009: Published
- 16 June 2026: Record last updated

### How Precursor Intelligence ranks it

CVE-2009-1123 scores **74 out of 100 (High)**, with the action "Emergency patch".

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-2009-1123?

The published record lists 5 products.

- [Windows 2000](https://www.precursorintelligence.com/product/microsoft/windows_2000) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows Server 2003](https://www.precursorintelligence.com/product/microsoft/windows_server_2003) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows Server 2008](https://www.precursorintelligence.com/product/microsoft/windows_server_2008) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows Vista](https://www.precursorintelligence.com/product/microsoft/windows_vista) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows Xp](https://www.precursorintelligence.com/product/microsoft/windows_xp) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified

## How do I fix CVE-2009-1123?

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. **Check it wasn’t used before you patched.** Because criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.

### References

- [docs.microsoft.com](https://docs.microsoft.com/en-us/security-updates/securitybulletins/2009/ms09-025) (Patch, Vendor advisory)
- [osvdb.org](http://osvdb.org/54940) (Broken link)
- [secunia.com](http://secunia.com/advisories/35372) (Broken link)
- [securitytracker.com](http://www.securitytracker.com/id?1022359) (Broken link, Third-party advisory, Vulnerability database)
- [us-cert.gov](http://www.us-cert.gov/cas/techalerts/TA09-160A.html) (Broken link, Third-party advisory, Government resource)
- [vupen.com](http://www.vupen.com/english/advisories/2009/1544) (Broken link)
- [oval.cisecurity.org](https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A6206) (Broken link)
- [cisa.gov](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2009-1123) (Government resource)

## Questions

### What is CVE-2009-1123?

CVE-2009-1123 is a high-severity flaw in Windows 2000 from Microsoft, published on 10 June 2009. An attacker has to be already on the device without logging in, but a person has to take an action first. If it works, the attacker can read data, change data and take it offline.

### How serious is CVE-2009-1123?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2009-1123 is 74 out of 100, which is High. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.

### Is CVE-2009-1123 being exploited?

Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 4.9%.

### Which versions does CVE-2009-1123 affect?

For Windows 2000 from Microsoft: version not specified. The record lists 5 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2009-1123?

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. Because criminals are already using it, also check affected systems for signs of a break-in.

## Does CVE-2009-1123 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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