Firefox JIT miscompilation in JS WebAssembly component (CVE-2026-12321)
CVE-2026-12321 Published on June 16, 2026
JIT miscompilation in the JavaScript: WebAssembly component
JIT miscompilation in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 152 and Thunderbird 152.
Vulnerability Analysis
CVE-2026-12321 can be exploited with network access, requires user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Always-Incorrect Control Flow Implementation
The code contains a control flow path that does not reflect the algorithm that the path is intended to implement, leading to incorrect behavior any time this path is navigated. This weakness captures cases in which a particular code segment is always incorrect with respect to the algorithm that it is implementing. For example, if a C programmer intends to include multiple statements in a single block but does not include the enclosing braces (CWE-483), then the logic is always incorrect. This issue is in contrast to most weaknesses in which the code usually behaves correctly, except when it is externally manipulated in malicious ways.
Products Associated with CVE-2026-12321
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Affected Versions
Mozilla Firefox:- Version 152, <= * is unaffected.
- Version 152, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.