HOMEVULNERABILITIESCVE-2026-2636
MEDIUM

CVE-2026-2636

CWE-159Published: February 25, 2026· Updated: Feb 27, 2026

5.5
CVSS v3.1
EPSS:0.04%probability of exploitation in 30 daysPercentile:11.1th

Official Description

This vulnerability is caused by a CWE‑159: "Improper Handling of Invalid Use of Special Elements" weakness, which leads to an unrecoverable inconsistency in the CLFS.sys driver. This condition forces a call to the KeBugCheckEx function, allowing an unprivileged user to trigger a system crash. Microsoft silently fixed this vulnerability in the September 2025 cumulative update for Windows 11 2024 LTSC and Windows Server 2025. Windows 25H2 (released in September) was released with the patch. Windows 1123h2 and earlier versions remain vulnerable.

NVD Source

Technical Analysis

CVE-2026-2636 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 5.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

Mentioned vendors (from description):
Microsoft
CPE data not yet available in NVD for this CVE.

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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All References (1)

→
https://www.fortra.com/security/advisories/research/fr-2026-001

Quick Facts

CVE IDCVE-2026-2636
CVSS Score5.5 / 10
SeverityMEDIUM
WeaknessCWE-159
CISA KEVNo
EPSS (30d)0.04%
PublishedFeb 25, 2026

Related CVEs (CWE-159)

CVE-2026-35536
7.2

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-2636 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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