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PatchSiren cyber security CVE debrief

CVE-2026-70309 Microsoft CVE debrief

Microsoft Edge (Chromium-based) Security Feature Bypass Vulnerability allows an unauthorized attacker to bypass a security feature over a network due to an origin validation error. This vulnerability, with a CVSS score of 5.4 and MEDIUM severity, requires defenders to assess exposure and prioritize patching to prevent potential security feature bypasses. The vulnerability affects Microsoft Edge (Chromium-based) versions prior to 150.0.4078.65. Defenders responsible for managing and securing Microsoft Edge (Chromium-based) deployments should verify and apply patches to prevent potential security risks.

Vendor
Microsoft
Product
Microsoft Edge (Chromium-based)
CVSS
MEDIUM 5.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-08-28
Original CVE updated
2026-10-08
Advisory published
2026-08-28
Advisory updated
2026-10-08

Who should care

Defenders responsible for managing and securing Microsoft Edge (Chromium-based) deployments should assess exposure and prioritize patching to prevent potential security feature bypasses.

Why it matters

CVE-2026-70309 is a security feature bypass vulnerability in Microsoft Edge (Chromium-based) that defenders should prioritize patching to prevent potential security risks. The vulnerability has a CVSS score of 5.4 and MEDIUM severity. Defenders responsible for managing and securing Microsoft Edge (Chromium-based) deployments should assess exposure and prioritize patching. The vulnerability requires verification of Microsoft Edge (Chromium-based) versions and potential updates to ensure version 150.0.4078.65 or later is deployed.

  • Defenders need to verify and apply patches to prevent potential security feature bypasses.
  • Security teams should review network configurations to ensure proper security features are enabled and configured.
  • Patch management and vulnerability management teams should prioritize this CVE for Microsoft Edge (Chromium-based) deployments.

Technical summary

The vulnerability is caused by an origin validation error in Microsoft Edge (Chromium-based), allowing an unauthorized attacker to bypass a security feature over a network. The CVSS score is 5.4, indicating a MEDIUM severity. This vulnerability affects Microsoft Edge (Chromium-based) versions prior to 150.0.4078.65. Defenders should prioritize verifying and applying patches for Microsoft Edge (Chromium-based) to prevent potential security feature bypasses. The vulnerability requires verification of Microsoft Edge (Chromium-based) versions and potential updates to

Defensive priority

Defenders should prioritize verifying and applying patches for Microsoft Edge (Chromium-based) to prevent potential security feature bypasses.

Recommended defensive actions

  • Verify and apply patches for Microsoft Edge (Chromium-based) to prevent potential security feature bypasses.
  • Monitor Microsoft Edge (Chromium-based) versions for updates and ensure version 150.0.4078.65 or later is deployed.
  • Review network configurations to ensure proper security features are enabled and configured.

Evidence notes

The CVE record and source item provide details on the vulnerability, including its CVSS score of 5.4 and MEDIUM severity. Microsoft Edge (Chromium-based) versions prior to 150.0.4078.65 are affected.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-70309 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-70309

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-70309 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-70309

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.