Microsoft Office Outlook: Heap-based buffer overflow allows remote code execution
Summary
A heap-based buffer overflow in Microsoft Outlook, part of Microsoft 365 Apps and Office LTSC 2021/2024, allows an unauthorized attacker to execute code over a network. User interaction is required, for example by opening a malicious message or file. Microsoft rates the impact as high for confidentiality, integrity and availability. Exploitation is not known, and CISA SSVC lists exploitation as none.
Affected
- Microsoft 365 Apps for Enterprise (16.0.1 up to the fixed build, see Microsoft advisory)
- Microsoft Office LTSC 2021 (16.0.1 to before 16.0.14334.20974, per CVE record)
- Microsoft Office LTSC 2024 (16.0.0 to before 16.0.17932.21056, per CVE record)
- Unsupported Outlook versions (2016, 2019, 2021 end of support) will not receive a fix
Fixed in
- Security update published by Microsoft on October 13, 2026 for each affected edition
- Exact fixed build numbers for each channel: Unknown. Check the MSRC advisory before rollout.
Workaround
- Unknown. No Microsoft-documented workaround found. Apply the security update.
Exploitation
- Not known to be exploited in the wild; not listed in CISA KEV.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
Our recommendation
- Deploy the October 2026 security updates for Microsoft 365 Apps and Office LTSC 2021/2024 to all Outlook clients.
- Confirm the fixed build numbers on the MSRC page and set minimum builds per channel.
- Identify Outlook 2016, 2019 or 2021 clients and plan their upgrade.
- Monitor CISA KEV and the Microsoft advisory for changes in exploitation status.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-70282 msrc.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- OpenCVE: CVE-2026-70282 app.opencve.io
- Qualys Patch Tuesday October 2026 review blog.qualys.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 18:45.
Original description (NVD)
Heap-based buffer overflow in Microsoft Office Outlook allows an unauthorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.