Microsoft Office Outlook: Heap-based buffer overflow allows remote code execution
Summary
Microsoft Office Outlook contains a heap-based buffer overflow (CWE-122). According to the CVE record, an unauthorized attacker can execute code over a network. The CVSS vector requires high attack complexity and user interaction, and the impact on confidentiality, integrity and availability is rated high. Exploitation of this specific CVE is not confirmed.
Affected
- Microsoft 365 Apps for Enterprise: 16.0.1 up to the fixed build (exact build unknown, see Microsoft advisory)
- Office LTSC 2021: 16.0.1 before 16.0.14334.21048
- Office LTSC 2024: 16.0.0 before 16.0.17932.21140
Fixed in
- Office LTSC 2021: 16.0.14334.21048
- Office LTSC 2024: 16.0.17932.21140
- Microsoft 365 Apps for Enterprise: November 2026 security update for the installed update channel (exact build unknown, see https://aka.ms/OfficeSecurityReleases)
Workaround
Unknown. No official workaround has been identified; patching is the priority.
- General measures, not from the sources: restrict outbound SMB (TCP 445) and NTLM where feasible, and limit email preview and external content where policy allows.
Exploitation
- Unknown for this CVE.
- CISA SSVC assessment: exploitation none, automatable no, technical impact total.
- A link to an Outlook zero-day exploited in November 2026 has been reported but is unconfirmed; that zero-day is described differently.
- No public proof of concept found; the CVE is reported as not listed in CISA KEV.
Our recommendation
- Update Microsoft Office Outlook to the fixed builds listed above, and confirm the installed build on all Outlook clients.
- For Microsoft 365 installations, verify that the November 2026 security update has been applied on the deployed update channel.
- Check the Microsoft advisory for the exact fixed build of Microsoft 365 Apps for Enterprise and for any updated exploitation status.
- Monitor for exploitation indicators and prioritise the update where Outlook on Windows is used with Microsoft 365 or Office LTSC.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- CVE.org record CVE-2026-119996 www.cve.org
- Microsoft Security Update Guide CVE-2026-119996 msrc.microsoft.com
- Rapid7 Patch Tuesday November 2026 (CVSS conflict) www.rapid7.com
- BleepingComputer: November 2026 Patch Tuesday www.bleepingcomputer.com
- Cryptika: Outlook zero-day report www.cryptika.com
- Strix: CVE-2026-119996 www.strix.ai
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 11 Nov 2026, 05:23.
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.
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