CVE-2013-3661

MEDIUMCVSS v2 · 4.94.9—
EchelonGraph scoreLOW confidence

This CVE was only ever scored under CVSS v2.0. NVD CVSS v2.0 base 4.9 — v2 rates that MEDIUM (v2 bands: LOW 0.0–3.9 / MEDIUM 4.0–6.9 / HIGH 7.0–10.0; v2 has no CRITICAL band). Vector AV:L/AC:L/Au:N/C:N/I:N/A:C. CVSS v2 is an older, coarser metric than v3.1/v4.0 (no Scope, no User Interaction, no Attack Requirements), so it is not directly comparable to a v3 or v4 score. NVD has never re-scored this record under v3. EPSS predicts 3.9% exploitation probability in the next 30 days, which is reflected in EG Risk but does not lift the v2 base. Confidence: LOW.

Sources: epss, nvd_v2
Weaponized
4.9EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 4%CVSS v2: 4.9Exploit: Exploit-DB (verified) · public exploitExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

The EPATHOBJ::bFlatten function in win32k.sys 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, Windows Server 2012, and Windows RT does not check whether linked-list traversal is continually accessing the same list member, which allows local users to cause a denial of service (infinite traversal) via vectors that trigger a crafted PATHRECORD chain.

CVSS v2.0 (legacy)
4.9MEDIUMNVD never assigned a CVSS v3 rating to this CVE
EG Score
4.9(low)
EG Risk
53(Track)
EG Risk 53/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity49% × 45%
Exploitation65% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
4%
EPSS %ILE
89%
KEV
Not listed

Published

May 24, 2013

Last Modified

April 29, 2026

References (18)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 34× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-26 13:48 UTCEG score recompute▲ 4.90
  2. 2026-07-25 14:12 UTCEPSS rescore
  3. 2026-07-23 14:14 UTCEPSS rescore
  4. 2026-07-23 01:10 UTCEG score recompute
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  7. 2026-07-22 14:04 UTCEPSS rescore
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  48. 2026-05-29 13:41 UTCEPSS rescore
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  50. 2026-05-28 23:49 UTCEG score recompute
  51. 2026-05-28 23:49 UTCGHSA enrichment
  52. 2026-05-28 13:42 UTCEPSS rescore
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Publicly available exploits

(3 references)

Working exploit code is in the public domain (3 Exploit-DB entries). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • Exploit-DBEDB-26554✓ verified
    First seen Jul 2, 2013

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

    Open source ↗
  • Exploit-DBEDB-25912✓ verified
    First seen Jun 3, 2013

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

    Open source ↗
  • Exploit-DBEDB-25611✓ verified
    First seen May 21, 2013

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

    Open source ↗

Related CVEs(same CWE)

Frequently asked(4)

What is CVE-2013-3661?
CVE-2013-3661 is a medium vulnerability published on May 24, 2013. The EPATHOBJ::bFlatten function in win32k.sys 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, Windows Server 2012, and Windows RT does not check whether linked-list traversal is continually accessing the…
When was CVE-2013-3661 disclosed?
CVE-2013-3661 was first published in the National Vulnerability Database on May 24, 2013, with the most recent update on April 29, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2013-3661 actively exploited?
CVE-2013-3661 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4% probability of exploitation in the next 30 days, which ranks it in the top 11.0% of all scored CVEs.
How do I remediate CVE-2013-3661?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2013-3661, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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