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CVE-2026-16368 Mozilla CVE debrief

CVE-2026-16368 is a critical vulnerability in the JavaScript: WebAssembly component due to incorrect boundary conditions. This issue affects Firefox, Firefox ESR, Thunderbird, and Thunderbird 140.13. The vulnerability was addressed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. The NVD entry is currently Undergoing Analysis. Affected organizations should prioritize updates for these products to prevent exploitation. The vulnerability has a critical CVSS score of 9.8, indicating a high severity level.

Vendor
Mozilla
Product
Firefox
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-21
Original CVE updated
2026-07-22
Advisory published
2026-07-21
Advisory updated
2026-07-22

Who should care

Users of Firefox, Firefox ESR, Thunderbird, and Thunderbird 140.13 should apply updates to prevent exploitation of CVE-2026-16368. This vulnerability has a critical CVSS score of 9.8 and may pose significant risk to affected systems. IT administrators and security teams responsible for these products should prioritize patching. Additionally, developers and users of WebAssembly components should be aware of the potential risks and take necessary precautions.

Technical summary

CVE-2026-16368 is a critical vulnerability in the JavaScript: WebAssembly component due to incorrect boundary conditions. This issue was addressed in Firefox 153, Firefox ESR 140.13, Thunderbird 153, and Thunderbird 140.13. Affected users should apply updates to prevent exploitation. The vulnerability affects Firefox, Firefox ESR, and Thunderbird products, posing significant risk due to its critical CVSS score of 9.8. Users of these products should prioritize applying updates to mitigate potential damage.

Defensive priority

High

Recommended defensive actions

  • Apply updates for Firefox to version 153 or later
  • Apply updates for Firefox ESR to version 140.13 or later
  • Apply updates for Thunderbird to version 153 or later
  • Apply updates for Thunderbird 140.13 or later
  • 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

Evidence notes

The CVE record and NVD entry provide details on the vulnerability. Additional information can be found in the Mozilla security advisories. Evidence is limited to public sources and may not reflect the full scope or impact of the vulnerability. Defenders should verify affected systems and apply updates or mitigations as recommended by the vendor. Further review of system logs and monitoring is necessary to detect potential exploitation attempts.

Official resources

AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-21T13:17:05.360Z and has not been modified since then. The NVD entry is currently Undergoing Analysis.