CVE-2026-26176
Published: 14 April 2026
Summary
CVE-2026-26176 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Windows 10 21H2. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 18.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-16 (Memory Protection) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-26176 is a heap-based buffer overflow vulnerability, classified under CWE-122, in the Windows Client Side Caching driver (csc.sys). This issue affects Windows systems that utilize the csc.sys driver for client-side caching functionality. Published on 2026-04-14T18:16:53.003, it carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to its potential for significant impact.
The vulnerability can be exploited by an authorized local attacker possessing low privileges. Exploitation requires local access with low attack complexity and no user interaction. Successful exploitation enables the attacker to elevate privileges locally, achieving high impacts on confidentiality, integrity, and availability.
Microsoft's Security Response Center advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26176 provides details on the vulnerability, including available patches and mitigation guidance for affected systems.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-22414
Vulnerability details
Heap-based buffer overflow in Windows Client Side Caching driver (csc.sys) allows an authorized attacker to elevate privileges locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap-based buffer overflow in kernel driver (csc.sys) with local attack vector and low privileges directly enables local privilege escalation via vulnerability exploitation.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly remediates the heap-based buffer overflow vulnerability in csc.sys by identifying, reporting, and applying vendor patches in a timely manner.
Implements memory protection mechanisms such as DEP and ASLR that prevent successful exploitation of heap buffer overflows in kernel drivers like csc.sys.
Validates and restricts inputs to the csc.sys driver to prevent malformed data from triggering the heap-based buffer overflow.