CVE-2026-70329 — Microsoft 365 Apps
HIGHCVE-2026-70329 is a high-severity (CVSS 8.8) CWE-190 vulnerability in microsoft 365 apps. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.
Integer overflow or wraparound in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-70329.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Description
Integer overflow or wraparound in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
Affected Products
365 appsmicrosoftoffice 2019microsoftoffice 2021microsoftoffice 2024microsoftoutlookmicrosoftDetection & mitigation playbook
Vendor / applianceDetect
Inventory every microsoft 365 apps deployment and check each version against the affected-products list above.
Remediation status
The records we use list no fixed version for CVE-2026-70329. Check the microsoft 365 apps advisory for a patched release, and apply the workarounds below until you can upgrade.
Mitigate without a patch
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
Frequently Asked Questions
Is CVE-2026-70329 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.