Microsoft Office Outlook: Remote code execution via double free
Summary
A double free weakness (CWE-415) in Microsoft Office Outlook allows an unauthenticated remote attacker to execute code. Microsoft rates it Critical (CVSS 9.8) and describes it as network-reachable with no privileges and no user interaction. According to the advisory text cited in the research notes, simply viewing a crafted message in the Reading Pane could trigger it, so email is the main attack path.
Affected
- Microsoft 365 Apps for Enterprise (32-bit and 64-bit), from 16.0.1 up to the fix referenced at aka.ms/OfficeSecurityReleases
- Office LTSC 2021, from 16.0.1 (fixed build reported only by a third-party aggregator as 16.0.14334.20974, unverified)
- Office LTSC 2024, from 16.0.0 (fixed build reported only by a third-party aggregator as 16.0.17932.21056, unverified)
Fixed in
- Exact fixed build per channel: Unknown. Use the Security Updates table on the MSRC advisory for the authoritative build.
- Office LTSC 2021: Unknown. Sources conflict on whether it received this update or reached end of support on October 13, 2026.
- Microsoft 365 Apps: current builds from the October 2026 security release are listed by Microsoft, but CVE-2026-97749 could not be confirmed in the retrieved list.
Workaround
- No vendor workaround found: Unknown.
- Reducing Reading Pane exposure is a reasonable interim step, but this is a general recommendation and not a documented mitigation for this CVE.
Exploitation
- Exploited in the wild: none reported.
- Microsoft temporal rating E:U (Unproven); exploitability assessment 'Exploitation Less Likely'.
- CISA SSVC: exploitation none, automatable yes.
- Not listed in CISA KEV.
- No public proof-of-concept found in searches; this does not prove none exists.
Our recommendation
- Patch Microsoft 365 Apps and Office LTSC clients immediately, prioritising mail-facing systems.
- Verify the installed Outlook build on every endpoint against the MSRC advisory table.
- Check LTSC 2021 support status with Microsoft before deciding how to remediate those clients.
- Monitor for exploitation indicators and suspicious inbound mail until all clients are confirmed patched.
Information from Microsoft (Patch Tuesday October 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-97749 msrc.microsoft.com
- MSRC advisory CVE-2026-97749 msrc.microsoft.com
- Microsoft 365 Apps security updates learn.microsoft.com
- Robert 365: Latest updates for classic Outlook robert365.com
- Rapid7: Patch Tuesday October 2026 www.rapid7.com
- Talos: Microsoft Patch Tuesday October 2026 blog.talosintelligence.com
- OpenCVE: CVE-2026-97749 app.opencve.io
- Vulners: CVE-2026-97749 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 30 Oct 2026, 18:13.
Original description (NVD)
Double free 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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