# CVE-2026-66315: Microsoft Edge use-after-free vulnerability in Chromium

Source: https://junglewise.ai/threats/cve-2026-66315-microsoft-edge-use-after-free-vulnerability-in-chromium  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-04. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-66315 · Severity: high · CVSS 7.5 · Published 2026-08-04

Microsoft Edge is a web browser used by millions of users worldwide. A use-after-free memory flaw allows attackers to execute arbitrary code on a user's system simply by serving a malicious webpage, potentially leading to complete system compromise, theft of sensitive data, or malware installation.

Technologies: [Microsoft Edge](https://junglewise.ai/threats/technologies/edge), [Microsoft Edge Chromium](https://junglewise.ai/threats/technologies/edge-chromium). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-66315 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66315 being exploited in the wild.

**How severe is CVE-2026-66315?** High severity, with a CVSS score of 7.5, published 4 August 2026.

**Which products and versions are affected?** Microsoft Edge <UNKNOWN>.

**Is there a fix for CVE-2026-66315?** 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-2026-66315 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-66315?** 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 use-after-free vulnerability exists in Microsoft Edge's Chromium-based rendering engine, where memory is accessed after being freed, leading to memory corruption. The flaw is reachable over the network and can be triggered by visiting a specially crafted malicious website. An attacker can exploit this vulnerability to achieve arbitrary code execution with the privileges of the user running the browser, without requiring user authentication or special privileges beyond visiting a webpage.

## Affected products

- Microsoft Edge <UNKNOWN>

## Timeline

- 2026-08-04: disclosed

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66315](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66315)

## Related threats

- [Microsoft Edge out-of-bounds read information disclosure](https://junglewise.ai/threats/cve-2026-122518-out-of-bounds-read-in-microsoft-edge-chromium-based-allows-an)
- [Microsoft Edge privilege escalation via incorrect authorization](https://junglewise.ai/threats/cve-2026-69446-incorrect-authorization-in-microsoft-edge-chromium-based-allows)
- [Microsoft Edge use-after-free privilege elevation](https://junglewise.ai/threats/cve-2026-96203-use-after-free-in-microsoft-edge-chromium-based-allows-an)
- [Microsoft Edge heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-96199-heap-based-buffer-overflow-in-microsoft-edge-chromium-based)
- [Microsoft Edge heap-based buffer overflow](https://junglewise.ai/threats/cve-2026-96198-heap-based-buffer-overflow-in-microsoft-edge-chromium-based)