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CISA KEV · ACTIVELY EXPLOITED
HIGH severity

CVE-2013-3660 — Microsoft

HIGH

CVE-2013-3660 is a high-severity (CVSS 7.8) Buffer Overflow vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2022-03-28) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

The EPATHOBJ::pprFlattenRec function in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2…

Published
Updated
Affected
8 products
Patched
See advisory
Exploits
10 known
Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

  • Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2022-03-28. Federal agencies were required to remediate by 2022-04-18.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2013-3660.

EPSS Exploitation Probability

via FIRST.org ↗
39.3%probability of exploitation in next 30 days
Moderate Risk0.00%
Lower risk than most CVEs99th percentile — riskier than 99% of all scored CVEsHighest risk
30.4%46.3%62.2%78.1%69.2%39.6%39.6%39.3%39.3%Apr 26Sep 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2013-3660 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.

Description

The EPATHOBJ::pprFlattenRec function in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, and Windows Server 2012 does not properly initialize a pointer for the next object in a certain list, which allows local users to obtain write access to the PATHRECORD chain, and consequently gain privileges, by triggering excessive consumption of paged memory and then making many FlattenPath function calls, aka "Win32k Read AV Vulnerability."

Affected Products

8 products · 10 configurations
OS
windows 7microsoft
all
OS
windows 8microsoft
all
OS
windows rtmicrosoft
all
OS
windows server 2003microsoft
all
OS
windows server 2008microsoft
1 version
r2
OS
windows server 2012microsoft
all
Exploits & PoCs
10

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-25611doswindows✓ Verified

Microsoft Windows - Win32k!EPATHOBJ::pprFlattenRec Uninitialized Next Pointer Testcase

by Tavis Ormandy · May 21, 2013

EDB-26554localwindows✓ Verified

Microsoft Windows - 'EPATHOBJ::pprFlattenRec' Local Privilege Escalation (Metasploit)

by Metasploit · Jul 2, 2013

EDB-25912localwindows✓ Verified

Microsoft Windows NT/2000/2003/2008/XP/Vista/7/8 - 'EPATHOBJ' Local Ring

by Tavis Ormandy · Jun 3, 2013

Detection & mitigation playbook

Vulnerability
  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    No fixed release is recorded for CVE-2013-3660 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

The EPATHOBJ::pprFlattenRec function in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, and Windows Server 2012 does not properly initialize a pointer for the next object in a certain list, which allows local users to obtain write access to the PATHRECORD chain, and consequently gain privileges, by triggering excessive consumption of paged memory and then making many FlattenPath function calls, aka "Win32k Read AV Vulnerability."
O3 Security · Impact-Aware SCA

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CVE-2013-3660: Microsoft Memory Corruption (KEV)