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CVE-2026-92050 Mozilla CVE debrief

A critical vulnerability was found in the XPConnect component of Firefox and Thunderbird, allowing for a sandbox escape due to a race condition. This issue was fixed in Firefox 156 and Thunderbird 156. The vulnerability's impact requires verification from official sources, and its exploitation is not confirmed. Defenders should prioritize verifying exposure, especially in environments utilizing XPConnect, and ensure updates to version 156 or later. The CVE record and NVD entry provide details on the vulnerability, but additional information from Mozilla's security advisories is required for comprehensive understanding.

Vendor
Mozilla
Product
Firefox
CVSS
CRITICAL 9.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-15
Original CVE updated
2026-09-21
Advisory published
2026-09-15
Advisory updated
2026-09-21

Who should care

Defenders responsible for Firefox and Thunderbird deployments, especially in environments utilizing the XPConnect component, should assess exposure and verify versions.

Why it matters

CVE-2026-92050 is a critical vulnerability in the XPConnect component of Firefox and Thunderbird, allowing for sandbox escape due to a race condition. Defenders should prioritize verifying exposure, especially in environments utilizing XPConnect, and ensure updates to version 156 or later. The vulnerability's impact requires verification from official sources, and its exploitation is not confirmed.

  • Potential sandbox escape and arbitrary code execution in Firefox and Thunderbird instances.
  • Possible exploitation of vulnerable versions in enterprise environments.
  • Need for verification of Firefox and Thunderbird versions and deployment contexts.

Technical summary

The CVE-2026-92050 vulnerability is caused by a race condition in the XPConnect component of Firefox and Thunderbird. This allows for a sandbox escape, potentially leading to arbitrary code execution. The vulnerability was fixed in Firefox 156 and Thunderbird 156.

Defensive priority

Defenders should prioritize verifying exposure in their Firefox and Thunderbird deployments, especially in environments where the XPConnect component is utilized.

Recommended defensive actions

  • Verify Firefox and Thunderbird versions in use and ensure they are updated to 156 or later.
  • Review deployment contexts where XPConnect is utilized and assess potential exposure.
  • Monitor for any signs of exploitation or anomalous behavior in Firefox and Thunderbird instances.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, but additional information from Mozilla's security advisories is required for comprehensive understanding.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-92050 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-92050

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

  • CVE-2026-92050 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-92050

    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.