CVE-2026-12321mediumCWE-670

CVE-2026-12321: medium-severity vulnerability in Mozilla Firefox

JIT miscompilation in the JavaScript: WebAssembly component

Published

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 5.4epss 0.2%
exploitation probability
0.2%top 96% of all CVEs
observed exploitation
nono source reports it
JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N
Affected products
Mozilla · FirefoxMozilla · Thunderbird
Related CVEs — Mozilla Firefox

In the same product, most dangerous first.

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