Quick answers
- Is CVE-2026-42903 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-42903 being exploited in the wild.
- How severe is CVE-2026-42903?
- Medium severity, with a CVSS score of 6.5, published 9 June 2026.
- Which products and versions are affected?
- Microsoft Windows Kerberos.
- Is there a fix for CVE-2026-42903?
- 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-2026-42903 attacked?
- It is attacked over the network, in an operating system.
- Am I affected by CVE-2026-42903?
- Check whether you run Microsoft Windows Kerberos. 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
A NULL pointer dereference vulnerability (CWE-476) exists within the Microsoft Windows Kerberos implementation. The flaw is triggered when the service improperly handles specific malformed requests, leading to a process crash. An attacker must be authenticated (Low Privileges) to reach the vulnerable code path over the network. Successful exploitation results in a denial of service (DoS) of the Kerberos authentication functionality, though it does not allow for information disclosure or remote code execution. Microsoft has released security updates to address this issue.
Affected products
- Microsoft Windows Kerberos
Timeline
- 2026-06-09: disclosed
- 2026-06-09: advisory