Microsoft Windows Open Type Font Remote Code Execution Vulnerability (CVE-2016-7256)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
atmfd.dll in the Windows font library in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, and 1607, and Windows Server 2016 allows remote attackers to execute arbitrary code via a crafted web site, aka "Open Type Font Remote Code Execution Vulnerability."
The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.
- Affected
- Microsoft Windows Server 2008
eq r2..r2 - Microsoft Windows Server 2012
eq r2..r2
- Microsoft Windows Server 2008
Not sure whether and how you are affected? Ask a question about this vulnerability
Metrics
8.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
8.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
64.6 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.24
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 222.79 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploited
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 64.6 %
- High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 99.24
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- CISA assessment (SSVC)
- Exploitation: active · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 10 February 2025
Response and mitigation
Why act now?
Prioritisation rationale
The flaw sits in a kernel-adjacent font parser and gives full system takeover from a crafted web page without authentication. The only requirement is that the user visits the page. Font-parsing bugs like this are staple material for drive-by and watering-hole campaigns, frequently serving as the sandbox-escape or privilege-escalation link in an exploit chain. Exploitation likelihood is very high, though CISA records no known ransomware use. In a fully patched Windows 10/11 estate the residual risk is low. Organisations running legacy Windows in OT, medical or production environments with any web access should treat it as high priority and close it quickly via patching, segmentation or the ATMFD workaround.
Runbook step 1
Immediate response (0-24 h)
- Apply the security update: The patch is available from the vendor. Look up the KB/bulletin number in the Microsoft advisory for CVE-2016-7256. Any current cumulative update or Monthly Rollup for the affected Windows versions should include the fix. Confirm coverage via WSUS/SCCM/Intune compliance reporting.
- Inventory legacy hosts: Find every asset running Windows Vista SP2, 7 SP1, 8.1, RT 8.1, Server 2008/2008 R2 or Server 2012/2012 R2. Include unpatched Windows 10 1507, 1511 and 1607 and Server 2016. Pay special attention to OT HMIs, kiosks, engineering workstations and embedded builds with no patch pipeline.
- Cut web access on unpatchable systems: The delivery vector is a crafted website. Block browsing from unpatched legacy hosts immediately via proxy policy or a firewall rule that denies outbound HTTP/HTTPS except to an allowlist.
- Disable the ATMFD font driver (workaround): Set
HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows→DisableATMFD(DWORD) =1, then reboot. This only affects Adobe Type 1/OpenType CFF rendering. Validate business applications first. - Check exposed legacy hosts for compromise: Run an EDR sweep for unusual child processes of browsers and Office apps, plus new services or autoruns created since the last known-good state.
Runbook step 2
Mitigation layers
- Endpoint hardening: On Windows 10, configure the GPO "Computer Configuration → Administrative Templates → System → Mitigation Options → Untrusted Font Blocking" to "Block untrusted fonts and log events". This blocks fonts loaded from outside
%windir%\Fonts. Roll it out in audit mode first. - Network / proxy: On the secure web gateway, block or inspect font downloads to legacy segments. Cover the MIME types
font/otf,application/vnd.ms-opentype,application/x-font-otfandfont/sfnt, and the extensions.otf,.ttfand.pfb. At the mail gateway, sandbox or quarantine Office documents that carry embedded fonts. - Segmentation: Move unpatchable Windows 7/2008/Vista hosts into a dedicated VLAN with no direct internet egress. Allow admin access only via a jump host, and filter lateral SMB/RDP from that segment tightly.
- IAM / least privilege: Exploitation yields kernel-level code execution, so user rights alone won't contain it. Still remove local admin rights and keep sandboxed browsers current. Consider remote browser isolation for legacy endpoints.
- Lifecycle: Most affected OS versions are end-of-support. Document migration or ESU coverage as a formal risk acceptance in the ISMS (ISO 27001 A.8.8, NIS2 Art. 21).
- Endpoint hardening: On Windows 10, configure the GPO "Computer Configuration → Administrative Templates → System → Mitigation Options → Untrusted Font Blocking" to "Block untrusted fonts and log events". This blocks fonts loaded from outside
Runbook step 3
Detection rules
- Crash artefacts from failed exploitation: Look for System log Event ID 1001 (BugCheck) or 41 (Kernel-Power), particularly shortly after browsing. A minidump implicating
atmfd.dll/win32k.sysis a strong signal. KQL:Event | where EventLog=="System" and EventID==1001 and RenderedDescription has_any ("atmfd","win32k") - Process ancestry (Sysmon EID 1 / Security 4688): Alert when a browser (
iexplore.exe,chrome.exe,firefox.exe,msedge.exe) or an Office app spawnscmd.exe,powershell.exe,rundll32.exeorregsvr32.exe. A SYSTEM-integrity child under a low/medium-integrity parent is especially suspicious. Sigma shape:ParentImage|endswith: [browser list] AND Image|endswith: [shell list] - Font files dropped in temp paths (Sysmon EID 11): Watch for a browser or Office process writing
.otf/.ttf/.pfbto%TEMP%,INetCacheorAppData\Local\Packages. Correlate with a subsequent EID 1 from the same parent. - Untrusted Font Blocking events: With the mitigation enabled, entries appear in
Microsoft-Windows-Win32k/Operational. A sudden spike on individual hosts suggests delivery attempts. - Network (Zeek/Suricata): Hunt
files.logfor font MIME types served from rare or newly registered domains. Enable the Emerging Threats signatures for malformed OpenType/CFF fonts and cross-reference hits against the target host's patch level.
- Crash artefacts from failed exploitation: Look for System log Event ID 1001 (BugCheck) or 41 (Kernel-Power), particularly shortly after browsing. A minidump implicating
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
atmfd.dll in the Windows font library in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, and 1607, and Windows Server 2016 allows remote attackers to execute arbitrary code via a crafted web site, aka "Open Type Font Remote Code Execution Vulnerability."
Source: NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)
Vendors and products
- Microsoft Windows 10 1507
- Microsoft Windows 10 1511
- Microsoft Microsoft Windows 10 1607
- Microsoft Microsoft Windows 7
- Microsoft Microsoft Windows 8.1
- Microsoft Microsoft Windows RT 8.1
- Microsoft Microsoft Windows Server 2008
- Microsoft Microsoft Windows Server 2012
- Microsoft Microsoft Windows Server 2016
- Microsoft Microsoft Windows Vista Gold on X64
Affected operating systems
| Windows | microsoft | windows_10_1507 | — |
| Windows | microsoft | windows_10_1511 | — |
| Windows | microsoft | windows_10_1607 | — |
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_8.1 | — |
| Windows | microsoft | windows_rt_8.1 | — |
| Windows | microsoft | windows_server_2008 | r2 |
| Windows | microsoft | windows_server_2008 | — |
| Windows | microsoft | windows_server_2012 | r2 |
| Windows | microsoft | windows_server_2012 | — |
| Windows | microsoft | windows_server_2016 | — |
| Windows | microsoft | windows_vista | — |
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited |
References & sources
- twitter.comda5ch0/status/820161895269277696x_refsource_MISC, Broken link
- securitytracker.com1037243Vulnerability database, x_refsource_SECTRACK, Broken link, Third-party advisory, Vulnerability database
- docs.microsoft.comMS16-132Vendor advisory, x_refsource_MS, Patch, Vendor advisory
- securityfocus.com94156Vulnerability database, x_refsource_BID, Broken link, Third-party advisory, Vulnerability database
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2016-7256government-resource, US government resource
Embed badge
Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.
<a href="https://intel.neosec.eu/en/cve/CVE-2016-7256"><img src="https://intel.neosec.eu/badge/cve/CVE-2016-7256.svg?lang=en" alt="CVE-2016-7256 – NEOSEC Intel" height="20"></a>