CVE-2026-92059 Mozilla CVE debrief

Who should care

Defenders responsible for Mozilla products, specifically those using Firefox, Firefox ESR, Thunderbird, should assess exposure and apply patches if necessary. Defenders should prioritize verification of exposure in Firefox, Firefox ESR, Thunderbird, and other Mozilla products, assessing if software versions are earlier than the patched versions. Defenders should verify exposure, assess if software versions are vulnerable, and apply patches if necessary.

Why it matters

CVE-2026-92059 is a critical vulnerability in Mozilla products, specifically in the DOM: Editor component. Defenders should verify exposure, assess if software versions are vulnerable, and apply patches if necessary.

• Verification of exposure in Mozilla products is required.
• Applying patches from Mozilla may be necessary to prevent exploitation.
• Defenders should assess if software versions are earlier than the patched versions.

Technical summary

The vulnerability is due to incorrect boundary conditions in the DOM: Editor component. It was fixed in Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3. The vulnerability has a CVSS score of 9.3 and is classified as CRITICAL. Defenders should prioritize verification of exposure in Firefox, Firefox ESR, Thunderbird, and other Mozilla products, assessing if software versions are earlier than the patched versions. Verification of exposure in Mozilla products is required. Applying patches from Mozilla may be necessary to prevent exploitation.

Defensive priority

Defenders should prioritize verification of exposure in Firefox, Firefox ESR, Thunderbird, and other Mozilla products, assessing if software versions are earlier than the patched versions.

Recommended defensive actions

• Verify if software versions are earlier than Firefox 156, Firefox ESR 153.3, Thunderbird 156, and Thunderbird 153.3.
• Assess exposure in Mozilla products.
• Apply patches from Mozilla if vulnerable.
• Review compensating controls for exposed systems while remediation is scheduled and verified.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description and CVSS score of 9.3. Mozilla has released advisories related to this vulnerability. The CVE record was published on 2026-09-15T13:17:00.350Z and has not been modified since then. The NVD entry is currently Awaiting Analysis. Defenders should verify exposure, assess if software versions are vulnerable, and apply patches if necessary. The vulnerability is due to incorrect boundary conditions in the DOM: Editor component. It was fixed in

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.