Quick answers
- Is CVE-2026-78520 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-78520 being exploited in the wild.
- How severe is CVE-2026-78520?
- Medium severity, with a CVSS score of 6.5, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Office Outlook.
- Is there a fix for CVE-2026-78520?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-78520 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-78520?
- Check whether you run Microsoft Office Outlook. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This vulnerability is an out-of-bounds read in Microsoft Office Outlook that permits remote code execution (RCE). The flaw is triggered when processing specially crafted email messages received over the network, requiring no user authentication to the vulnerable component itself. An attacker can exploit this by sending a malicious email that, when processed by Outlook, causes memory to be read outside allocated bounds, enabling arbitrary code execution in the context of the affected user. Network reachability is the primary requirement; the vulnerability does not appear to require user interaction beyond receiving the email. Microsoft has issued a security update to address this vulnerability.
Affected products
- Microsoft Office Outlook
Timeline
- 2026-09-08: disclosed