Quick answers
- Is CVE-2026-66321 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-66321 being exploited in the wild.
- How severe is CVE-2026-66321?
- High severity, with a CVSS score of 7.4, published 4 August 2026.
- Which products and versions are affected?
- Microsoft Edge Chromium-based versions.
- Is there a fix for CVE-2026-66321?
- 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-2026-66321 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-66321?
- Check whether you run Microsoft Edge or Microsoft Edge Chromium 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
A type confusion vulnerability exists in Microsoft Edge (Chromium-based) where incompatible resource types are accessed without proper validation. This vulnerability is in the browser's rendering or JavaScript engine and can be triggered remotely over a network when a user visits a malicious webpage. No authentication is required for exploitation. A successful attack allows remote code execution with the privileges of the logged-in user. Patches are expected to be available through Microsoft's regular security update cycle.
Affected products
- Microsoft Edge Chromium-based versions
Timeline
- 2026-08-04: disclosed