PT-2026-49690 · Mozilla · Firefox+1

Junyoung Park · Published 2026-06-16 · Updated 2026-06-16 · CVE-2026-12321

Positive Technologies (AI Summary)

CVSS v3.1

5.4

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Firefox versions prior to 152 Thunderbird versions prior to 152

Description JIT miscompilation occurs in the JavaScript: WebAssembly component. Just-In-Time (JIT) compilation is a method used to improve the execution speed of programs by compiling code during runtime rather than before execution.

Recommendations Update Firefox to version 152. Update Thunderbird to version 152.

Fix

Weakness Enumeration

CWE-670

Related Identifiers

CVE-2026-12321

Affected Products

Firefox

Thunderbird

References · 5

• https://nvd.nist.gov/vuln/detail/CVE-2026-12321 · Security Note
• https://mozilla.org/security/advisories/mfsa2026-57 · Vendor Advisory
• https://mozilla.org/security/advisories/mfsa2026-60 · Vendor Advisory
• https://twitter.com/VulmonFeeds/status/2066920554066526242 · Twitter Post
• https://bugzilla.mozilla.org/show_bug.cgi?id=2032943 · Note