CVE-2026-6770 Mozilla CVE debrief

Who should care

Defenders responsible for Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR deployments should assess exposure and apply patches to prevent potential exploitation of this vulnerability.

Why it matters

This vulnerability in the Storage: IndexedDB component of Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR requires verification of exposure and prompt patching to prevent potential exploitation.

• Verify exposure of Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR to this vulnerability
• Apply patches for Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR to the latest versions
• Review and update inventory of Mozilla products to ensure accurate tracking of vulnerable versions

Technical summary

The vulnerability is located in the Storage: IndexedDB component of Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR. It was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. The vulnerability requires verification of exposure and prompt patching to prevent potential exploitation. Defenders should prioritize verifying exposure and applying patches for Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR, especially for versions prior to the fixed versions. The vulnerability affects the Storage: IndexedDB component, which is used by these products.

Defensive priority

Defenders should prioritize verifying exposure and applying patches for Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR, especially for versions prior to the fixed versions.

Recommended defensive actions

• Verify exposure of Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR installations to this vulnerability
• Apply patches for Mozilla Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR to the latest versions
• Review and update inventory of Mozilla products to ensure accurate tracking of vulnerable versions
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected products. Vendor advisories are available for Mozilla products. The vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. Defenders should verify exposure and apply patches to prevent potential exploitation. The CVE record was published on 2026-04-21T13:16:22.840Z and has not been modified since then.

Sources and 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.