Microsoft Office Outlook: Stack-based buffer overflow enables remote code execution
Summary
A stack-based buffer overflow (CWE-121) in Microsoft Office Outlook allows an unauthorized network attacker to execute code. According to the CVSS vector, the attack requires no privileges but user interaction, and it would fully compromise confidentiality, integrity and availability. The exact trigger and whether the Preview Pane is an attack vector are not verified.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 and later, up to the fixed build (exact upper bound unverified)
- Microsoft Office LTSC 2021: 16.0.1 up to but not including 16.0.14334.20974 (unverified)
- Microsoft Office LTSC 2024: 16.0.0 up to but not including 16.0.17932.21056 (unverified)
- Other channels named in Microsoft's release notes (Office 2019, Office 2024): unknown
Fixed in
- Install the Microsoft Office/Outlook security update from October 2026 (see the MSRC advisory).
- Exact fixed build per channel: Unknown. Confirm on the MSRC version table before rollout.
Workaround
- No Outlook-specific vendor workaround found.
- Interim measure (own recommendation, not a vendor mitigation): restrict mail-borne and link-based lures at the mail gateway and train users to avoid unexpected links and attachments.
Exploitation
- Not listed in CISA KEV at the time of research.
- CISA SSVC data in the CVE record: exploitation none, automatable no, technical impact total.
- Microsoft's assessment as reported by a third party: not publicly disclosed or exploited, rated Exploitation Less Likely (not verified on MSRC).
- No public proof of concept found. EPSS: unknown.
Our recommendation
- Patch all Outlook clients in the October 2026 update cycle; do not wait for exploitation signals.
- Verify the Outlook build on each client against the MSRC version table.
- Confirm that Microsoft 365 and LTSC installations are current, and find clients still running older Office builds.
- Check whether new Outlook (web-based) is in scope: Unknown.
- Recheck the MSRC advisory and CISA KEV for changes.
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 Response Center: CVE-2026-97012 msrc.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- Robert 365: Latest updates for classic Outlook robert365.com
- OpenCVE: CVE-2026-97012 app.opencve.io
- Qualys: Microsoft Patch Tuesday October 2026 review blog.qualys.com
- Strix: CVE-2026-97012 www.strix.ai
- Vulners: CVELIST CVE-2026-97012 vulners.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, 17:45.
Original description (NVD)
Stack-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.
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