Quick answers
- Is CVE-2026-66805 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-66805 being exploited in the wild.
- How severe is CVE-2026-66805?
- High severity, with a CVSS score of 8.8, published 11 August 2026.
- Which products and versions are affected?
- Microsoft Office SharePoint <UNKNOWN>.
- Is there a fix for CVE-2026-66805?
- 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-2026-66805 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-66805?
- Check whether you run Microsoft Office SharePoint at an affected version. 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
The vulnerability exists in Microsoft Office SharePoint's deserialization functionality, which improperly handles untrusted serialized data received over the network. The flaw allows an authorized attacker with network access to craft malicious serialized payloads that trigger arbitrary code execution on the affected SharePoint server. This is a classic insecure deserialization vulnerability (CWE-502) where untrusted input is deserialized without proper validation. The attack requires the attacker to have authorization to interact with the vulnerable component, limiting exposure but still posing a significant risk to compromised or disgruntled insiders. Patches are expected to be available through Microsoft's standard security update process.
Affected products
- Microsoft Office SharePoint <UNKNOWN>
Timeline
- 2026-08-11: disclosed