# What is CVE-2015-1671?

> CVE-2015-1671 is a high-severity flaw (CVSS 7.8) in .NET Framework from Microsoft, published on 13 May 2015. 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 49%. If you run an affected version, patch it first.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2015-1671

## 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:** 49% (latest exploit-likelihood forecast)
- **Published:** 13 May 2015
- **Record last updated:** 12 April 2025
- **Main product:** .NET Framework from Microsoft
- **Affected products:** 11

## What is CVE-2015-1671? 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 Windows DirectWrite library, as used in Microsoft .NET Framework 3.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, and 4.5.2; Office 2007 SP3 and 2010 SP2; Live Meeting 2007 Console; Lync 2010; Lync 2010 Attendee; Lync 2013 SP1; Lync Basic 2013 SP1; Silverlight 5 before 5.1.40416.00; and Silverlight 5 Developer Runtime before 5.1.40416.00, allows remote attackers to execute arbitrary code via a crafted TrueType font, aka "TrueType Font Parsing 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-2015-1671 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 49%.

Exploit likelihood over the last 7 days: 49%, 49%, 49%, 49%, 49%, 49%, 49%.

### Timeline

- 13 May 2015: Published
- 12 April 2025: Record last updated
- 16 June 2026: Exploit likelihood fell

### How Precursor Intelligence ranks it

CVE-2015-1671 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-2015-1671?

The published record lists 11 products.

- .NET Framework by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 3.0-sp2, 3.5, 3.5.1, 4.0, 4.5, 4.5.1, 4.5.2
- [Lync](https://www.precursorintelligence.com/product/microsoft/lync) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2010, 2013-sp1
- [Live Meeting](https://www.precursorintelligence.com/product/microsoft/live_meeting) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 2007
- [Silverlight](https://www.precursorintelligence.com/product/microsoft/silverlight) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): 5.0
- [Windows 7](https://www.precursorintelligence.com/product/microsoft/windows_7) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows 8](https://www.precursorintelligence.com/product/microsoft/windows_8) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified
- [Windows 8.1](https://www.precursorintelligence.com/product/microsoft/windows_8.1) 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): r2-sp1
- [Windows Server 2012](https://www.precursorintelligence.com/product/microsoft/windows_server_2012) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): r2
- [Windows Vista](https://www.precursorintelligence.com/product/microsoft/windows_vista) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Operating system): version not specified

## How do I fix CVE-2015-1671?

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/2015/ms15-044) (Patch, Vendor advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/74490) (Broken link, Third-party advisory, Vulnerability database)
- [securitytracker.com](http://www.securitytracker.com/id/1032281) (Broken link, Third-party advisory, Vulnerability database)

## Questions

### What is CVE-2015-1671?

CVE-2015-1671 is a high-severity flaw in .NET Framework from Microsoft, published on 13 May 2015. 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-2015-1671?

It scores 7.8 out of 10 on the CVSS severity scale, which is high. Our risk score for CVE-2015-1671 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-2015-1671 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 49%.

### Which versions does CVE-2015-1671 affect?

For .NET Framework from Microsoft: 3.0-sp2, 3.5, 3.5.1, 4.0, 4.5, 4.5.1 and 1 more. The record lists 11 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2015-1671?

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-2015-1671 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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