CVE-2026-12321 — MEDIUM (5.4)

Q: What is CVE-2026-12321?

CVE-2026-12321 is a vulnerability with a CVSS score of 5.4 (MEDIUM). JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

Q: How severe is CVE-2026-12321?

CVE-2026-12321 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.

Q: Is there a patch for CVE-2026-12321?

Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.

Vulnerability Description

JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

CVSS Score

5.4

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

LOW

Integrity

LOW

Availability

NONE

Affected Products

Vendor	Product	Versions
Mozilla	Firefox	< 152.0.0
Mozilla	Thunderbird	< 152.0.0

Related Weaknesses (CWE)

CWE-670

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2032943Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-57/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-60/Vendor Advisory

FAQ

What is CVE-2026-12321?

CVE-2026-12321 is a vulnerability with a CVSS score of 5.4 (MEDIUM). JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

How severe is CVE-2026-12321?

CVE-2026-12321 has been rated MEDIUM with a CVSS base score of 5.4/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-12321?

Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Firefox, Mozilla Thunderbird.