CVE-2026-26108
Published: 10 March 2026
Summary
CVE-2026-26108 is a high-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Microsoft Office Long Term Servicing Channel. Its CVSS base score is 7.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 7.7th 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).
Threat & Defense at a Glance
Threat & Defense Details
Mitigating Controls (NIST 800-53 r5)AI
Mandates monitoring, reporting, and timely remediation of flaws like the heap-based buffer overflow in Microsoft Office Excel through vendor patches.
Implements memory protections such as ASLR and DEP that directly mitigate exploitation of heap-based buffer overflows even if unpatched.
Deploys malicious code protection mechanisms to scan and block specially crafted Excel files before they trigger the buffer overflow.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap buffer overflow in Excel enables RCE via crafted file opened by user, mapping directly to client-side exploitation (T1203) and malicious file execution (T1204.002).
NVD Description
Heap-based buffer overflow in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Deeper analysisAI
CVE-2026-26108 is a heap-based buffer overflow vulnerability affecting Microsoft Office Excel, published on 2026-03-10T18:18:39.030. The issue, linked to CWE-122 and CWE-787, carries a CVSS v3.1 base score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating high severity due to its potential for significant impact.
An unauthorized attacker with local access can exploit the vulnerability by tricking a user into opening a specially crafted Excel file, requiring user interaction but no privileges or high complexity. Successful exploitation enables arbitrary code execution locally on the target system.
Microsoft's update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-26108 provides details on advisories and patches for mitigation.
Details
- CWE(s)