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🛡️ CVE-2026-2636

🟡 CVSS 5.5 — Medium ✅ No Known Exploit CWE-159 NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

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.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2026-2636 is classified as CWE-159: Improper Handling of Invalid Use of Special Elements. The product does not properly filter, remove, quote, or otherwise manage the invalid use of special elements in user-controlled input, which could cause adverse effect on its behavior and integrity.

Affected software

CVE-2026-2636 is recorded against 1 package.

  • unknown

Timeline and source

Published on 25 February 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

www.fortra.com

Other advisories for this package

unknown has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-159: Improper Handling of Invalid Use of Special Elements) in other software:

Details

Severity MEDIUM
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE CWE-159
Public Exploit ✅ No
Source NVD
Published 2026-02-25
Updated 2026-08-20
Modified 2026-06-17
Fix URL N/A

Affected Packages

Software From version Fixed in
unknown — —

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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