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CVE-2026-109774 Mozilla CVE debrief

Mozilla Firefox vulnerability CVE-2026-109774 involves an invalid pointer and undefined behavior in the DOM of the Notifications component. This issue was addressed in Firefox 158. Defenders should assess exposure and prioritize updates to mitigate potential risks associated with this vulnerability in Firefox versions prior to 158. The vulnerability could lead to undefined behavior, and defenders should verify exposure, assess impact, and prioritize updates accordingly. This vulnerability was fixed in Firefox 158.

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

Defenders responsible for managing Firefox installations should assess exposure and prioritize updates to mitigate potential risks associated with CVE-2026-109774. This includes verifying Firefox version and potential exposure, assessing vulnerability impact on systems, and monitoring for exploitation attempts. Security teams and vulnerability management teams should review this vulnerability and prioritize updates.

Why it matters

CVE-2026-109774 is a vulnerability in Firefox's Notifications component that could lead to undefined behavior. Defenders should verify exposure, assess impact, and prioritize updates to mitigate risks.

  • Verification of Firefox version and potential exposure
  • Assessment of vulnerability impact on systems
  • Monitoring for exploitation attempts

Technical summary

The vulnerability involves an invalid pointer and undefined behavior in the DOM of the Notifications component in Firefox. This issue was addressed in Firefox 158. The vulnerability could lead to undefined behavior in the DOM. Defenders should assess the technical impact of this vulnerability on Firefox installations and prioritize updates to mitigate risks. The technical details involve an invalid pointer issue that was fixed in Firefox 158.

Defensive priority

Defenders should prioritize verifying exposure in Firefox versions prior to 158 and assessing the impact of this vulnerability on their systems.

Recommended defensive actions

  • Verify Firefox version and update to 158 or later if necessary
  • Assess exposure and potential impact on systems
  • Monitor for potential exploitation attempts

Evidence notes

The vulnerability was reported in the Mozilla Bugzilla and fixed in Firefox 158. The CVE Program and NVD provide official records of this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-109774 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-109774

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

  • CVE-2026-109774 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-109774

    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.