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Firefox JIT miscompilation in JavaScript WebAssembly security flaw (CVE-2026-2796)

Vulnerability
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H score 39
1 unique sources, 1 articles

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Firefox 148 now addresses CVE-2026-2796, a CVSS 9.8 JIT miscompilation in the JavaScript WebAssembly component, after Anthropic validated the flaw and showed it could be turned into an exploit in testing. The broader finding set includes 22 Firefox vulnerabilities, with 14 high-severity bugs discovered during a two-week effort in January 2026. The disclosure matters because it ties a specific browser weakness to demonstrated exploit development, even though the exploit only worked in a constrained test environment.

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Timeline

  1. 07.03.2026 13:21 2 articles · 4mo ago

    Anthropic discloses Firefox CVE-2026-2796 findings

    Initial Disclosure

    Anthropic and Mozilla disclosed that Claude Opus 4.6 found 22 Firefox vulnerabilities during a January 2026 security effort, including CVE-2026-2796, a CVSS 9.8 just-in-time (JIT) miscompilation in the JavaScript WebAssembly component. Mozilla said the issues were fixed in Firefox 148, while Anthropic said its testing also produced a use-after-free finding in JavaScript and a small number of exploit successes in a stripped-down evaluation environment.

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