Quick answers
- Is CVE-2026-77891 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-77891 being exploited in the wild.
- How severe is CVE-2026-77891?
- Medium severity, with a CVSS score of 6.4, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Windows DHCP Server.
- Is there a fix for CVE-2026-77891?
- 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-2026-77891 attacked?
- It is attacked with local access.
- Am I affected by CVE-2026-77891?
- Check whether you run Microsoft Windows DHCP Server. 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
An out-of-bounds read vulnerability exists in Windows DHCP Server that allows an authenticated local attacker to read beyond allocated memory boundaries. The vulnerability requires the attacker to have local system access and valid credentials. Successful exploitation enables arbitrary code execution in the context of the DHCP Server process. A patch has been released by Microsoft; administrators should apply the security update promptly.
Affected products
- Microsoft Windows DHCP Server
Timeline
- 2026-09-08: disclosed