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CVE-2026-109749 Mozilla CVE debrief

Mozilla Firefox users should assess exposure to CVE-2026-109749, a use-after-free vulnerability in the JavaScript: WebAssembly component. Defenders should verify if their Firefox versions are prior to 158 and prioritize patching. The CVE Program and NVD provide official records, while Mozilla's security advisories offer remediation details. Affected product deployments require verification, and owners should be assigned for follow-up. The vulnerability's severity and scope should be validated using official advisories or CVE records.

Vendor
Mozilla
Product
Firefox
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-10-13
Original CVE updated
2026-10-13
Advisory published
2026-10-13
Advisory updated
2026-10-13

Who should care

Mozilla Firefox users and administrators should assess exposure to CVE-2026-109749 and prioritize patching to prevent potential exploitation.

Why it matters

CVE-2026-109749 is a use-after-free vulnerability in the JavaScript: WebAssembly component of Mozilla Firefox. Defenders should verify Firefox versions and prioritize patching to version 158 or later to address the vulnerability.

  • Defenders must verify Firefox versions and patch to version 158 or later to address the vulnerability.
  • Exposure to CVE-2026-109749 requires verification of Firefox versions and potential updates to prevent exploitation.
  • The vulnerability's impact on Firefox users requires prompt attention to prevent potential security breaches.

Technical summary

CVE-2026-109749 is a use-after-free vulnerability in the JavaScript: WebAssembly component of Mozilla Firefox. The vulnerability was fixed in Firefox 158. Defenders must verify Firefox versions and patch to version 158 or later to address the vulnerability. This vulnerability affects Mozilla Firefox users, who should review compensating controls for exposed systems while remediation is scheduled and verified.

Defensive priority

Patch Firefox to version 158 or later to address the use-after-free vulnerability.

Recommended defensive actions

  • Patch Firefox to version 158 or later
  • Verify Firefox version and update if necessary
  • Monitor Mozilla's security advisories for further information

Evidence notes

The CVE Program record and NVD vulnerability detail provide official information on CVE-2026-109749. Mozilla's security advisories offer remediation details.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-109749 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-109749

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

  • CVE-2026-109749 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-109749

    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.