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PatchSiren cyber security CVE debrief

CVE-2026-12304 Mozilla CVE debrief

A same-origin policy bypass vulnerability was discovered in the Networking: Cookies component of Firefox. This vulnerability, tracked as CVE-2026-12304, was fixed in Firefox 152 and Firefox ESR 140.12. The CVE was published on [cvePublishedAt](https://www.cve.org/CVERecord?id=CVE-2026-12304) and last modified on [cveModifiedAt](https://www.cve.org/CVERecord?id=CVE-2026-12304).

Vendor
Mozilla
Product
Firefox
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-16
Original CVE updated
2026-06-17
Advisory published
2026-06-16
Advisory updated
2026-06-17

Who should care

Users of Firefox and Firefox ESR should update to version 152 and 140.12 respectively to mitigate this vulnerability.

Technical summary

The vulnerability allows for a same-origin policy bypass in the Networking: Cookies component.

Defensive priority

high

Recommended defensive actions

  • Update Firefox to version 152 or later
  • Update Firefox ESR to version 140.12 or later

Evidence notes

The CVE was published by the CVE Program and details can be found on the [CVE-2026-12304 CVE record](cve-org). Additional information can be found on the [NVD detail page](nvd) and in the [source references](ref-4), [Mozilla security advisories](ref-5) and [Mozilla security advisories](ref-6).

Sources and references

Verified primary and authoritative sources

  • CVE-2026-12304 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-12304

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

  • CVE-2026-12304 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-12304

    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.