CVE-2026-40359
Published: 12 May 2026
Summary
CVE-2026-40359 is a high-severity Use After Free (CWE-416) 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 19.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-29641
Vulnerability details
Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Use-after-free in client app (Excel) directly enables arbitrary code execution via crafted document, mapping to Exploitation for Client Execution.
CVEs Like This One
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Use-after-free exploits that achieve arbitrary code execution are blocked or significantly hardened by non-executable pages and ASLR.