Quick answers
- Is CVE-2026-66303 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-66303 being exploited in the wild.
- How severe is CVE-2026-66303?
- Medium severity, with a CVSS score of 6.5, published 8 September 2026.
- Which products and versions are affected?
- Microsoft Skype for Business.
- Is there a fix for CVE-2026-66303?
- 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-2026-66303 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-66303?
- Check whether you run Microsoft Skype for Business. 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 exists in Skype for Business that can be triggered by an authorized/authenticated attacker over the network. The vulnerability occurs when the application attempts to dereference a null pointer without proper validation, leading to an application crash and denial of service. This requires the attacker to have valid authentication credentials to access the service. The specific vulnerable component and triggering conditions are not detailed in the available advisory text, but a patch from Microsoft is expected.
Affected products
- Microsoft Skype for Business
Timeline
- 2026-09-08: disclosed