High severityKnown ExploitedCVE-2019-17026

Mozilla Firefox And Thunderbird Type Confusion Vulnerability

Mozilla Firefox and Thunderbird contain a type confusion vulnerability due to incorrect alias information in the IonMonkey JIT compiler when setting array elements.

Published Nov 3, 2021Updated May 3, 2022Source checked Jul 18, 2026

Upstream Advisory

Key facts

Risk: High
Exploitation: Known exploited
Affected software: Not mapped
Fix availability: Not reported

Recommended action

Review the upstream advisory, identify the affected product in your inventory, and apply the vendor update when one is available.

What this means

Mozilla Firefox And Thunderbird Type Confusion Vulnerability is listed in the HOL Guard supply-chain feed, but affected software is not mapped to a package. Review the upstream advisory for the affected product and vendor guidance. This vulnerability is known to be exploited in the wild. Mozilla Firefox and Thunderbird contain a type confusion vulnerability due to incorrect alias information in the IonMonkey JIT compiler when setting array elements.

Affected software

Affected software not mapped. Review the upstream record for vendor-specific product and version guidance.

Evidence and references

No references were reported by the source.

Source metadata

Published: Nov 3, 2021
Modified: May 3, 2022
Source checked: Jul 18, 2026

Reported by CISA KEV (kev).

Keep this signal in your Guard workflow.

HOL Guard can help your team monitor supply-chain activity while the upstream record is clarified.

Explore HOL Guard

Back to active CVEs