# CVE-2026-66323: Microsoft Edge improper neutralization of parameter delimiters

Source: https://junglewise.ai/threats/cve-2026-66323-microsoft-edge-improper-neutralization-of-parameter-delimiters  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-28. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-66323 · Severity: medium · CVSS 5.4 · Published 2026-08-28

Microsoft Edge is a web browser used by millions of users for accessing websites and web applications. This vulnerability allows an attacker to execute malicious code remotely through improper handling of command-line arguments, potentially compromising user systems and data.

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-2026-66323 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-66323 being exploited in the wild.

**How severe is CVE-2026-66323?** Medium severity, with a CVSS score of 5.4, published 28 August 2026.

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

**Is there a fix for CVE-2026-66323?** 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-2026-66323 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-66323?** 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

This vulnerability stems from improper neutralization of parameter and argument delimiters in Microsoft Edge (Chromium-based). The flaw allows an unauthorized attacker to execute arbitrary code over a network without requiring authentication. The attack vector is network-based, meaning an attacker can exploit this remotely. Microsoft has released patches to address this issue.

## Affected products

- Microsoft Edge <UNKNOWN>

## Timeline

- 2026-08-28: disclosed
- 2026-08-28: advisory

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66323](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-66323)

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