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CVE-2026-40359
high
CVSS 7.8
Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
Summary
Use after free in Microsoft Office Excel allows an unauthorized attacker to execute code locally.
AI summary snake-internal / snake-template-v1
A weakness called CVE-2026-40359 was discovered in Microsoft Excel.
In plain terms, it is a use-after-free flaw that often leads to attacker takeover.
Severity is High (CVSS 7.8/10). If exploited, attackers can leak data or disrupt key functionality.
What you should do: update the affected software to the latest version. If unsure, ask your IT team or search the vendor's site for "Microsoft CVE-2026-40359".
CVE-2026-40359 (Microsoft Excel). Severity: High / CVSSv3 7.8. Category: CWE-416.
Response plan:
1. Check the vendor advisory for affected versions and the patched release.
2. If a vulnerable version is running in production, schedule maintenance (urgency from KEV/CVSS).
3. If no patch yet, mitigate via WAF rule, disabling the affected feature, etc.
4. Monitor logs / SIEM for known IOC and PoC signatures of this CVE.
PoCs and fix commits: see the 'References' section, MITRE, and NVD.
❓ What is the problem
A weakness (CVE-2026-40359) in Microsoft Excel. In plain words, it is a use-after-free flaw that often leads to attacker takeover.
📍 Affected scope
Target versions of Microsoft Excel (see vendor advisory). If running in production, identify exposure immediately.
🔥 Severity
Severity: High (CVSS 7.8/10). If exploited, attackers can leak data or disrupt key functionality.
🔧 How to fix
Update to the patched release as listed in the vendor advisory. (Typical mitigation pattern for CWE-416)
🛡️ Workaround
If a patch is not yet available, consider disabling the affected feature, applying WAF rules, blocking via network ACLs, or isolating the vulnerable version.
🔍 Detection
Check version information, scan dependencies via SBOM, and monitor SIEM for IOC and PoC signatures related to this CVE.