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CVE-2026-109749— Use-after-free in the JavaScript: WebAssembly component

Quick assessment

Affected
Mozilla Firefox
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

JavaScript: WebAssembly 组件中存在释放后使用（Use-after-free）漏洞。该漏洞已在 Firefox 158 中修复。

AI Predicted 7.8 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1206

Affected Version Matrix 2

VendorProduct Version RangeStatus
Mozilla Firefox 158≤ * unaffected
Mozilla Thunderbird 158≤ * unaffected
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I. Basic Information for CVE-2026-109749

Vulnerability Information
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Vulnerability Title
Use-after-free in the JavaScript: WebAssembly component
Source: CVE Program / CVE List V5
Vulnerability Description
Use-after-free in the JavaScript: WebAssembly component. This vulnerability was fixed in Firefox 158 and Thunderbird 158.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Mozilla Firefox 158 ~ * -
Mozilla Thunderbird 158 ~ * -

II. Public POCs for CVE-2026-109749

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III. Intelligence Information for CVE-2026-109749

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Other References for CVE-2026-109749 (2)

Same Patch Batch · Mozilla · 2026-10-13 · 83 CVEs total

CVE-2026-109731 Incorrect boundary conditions in the Graphics: Canvas2D component
CVE-2026-109713 Use-after-free in the Crash Reporting component
CVE-2026-109715 Incorrect boundary conditions in the JavaScript Engine component
CVE-2026-109733 JIT miscompilation in the JavaScript Engine: JIT component
CVE-2026-109728 Use-after-free in the DOM: Animation component
CVE-2026-109714 Incorrect boundary conditions in the Layout component
CVE-2026-109707 Sandbox escape due to use-after-free in the Networking component
CVE-2026-109720 JIT miscompilation in the JavaScript: WebAssembly component
CVE-2026-109776 Race condition in the XPCOM component
CVE-2026-109730 Integer overflow in the Graphics component
CVE-2026-109706 Use-after-free in the Storage: IndexedDB component
CVE-2026-109736 Frame poisoning in the Layout component
CVE-2026-109726 Use-after-free in the SVG component
CVE-2026-109748 Use-after-free in the JavaScript: WebAssembly component
CVE-2026-109705 Sandbox escape, site isolation issue due to incorrect boundary conditions, use-after-free
CVE-2026-109763 Mitigation bypass in the File Handling component
CVE-2026-109767 Information disclosure in the Networking component
CVE-2026-109751 Information disclosure in the Networking component
CVE-2026-109743 Privilege escalation in the Panning and Zooming component
CVE-2026-109732 Use-after-free in the DOM: Streams component

Showing top 20 of 83 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Firefox
Same vendor: Mozilla

V. Comments for CVE-2026-109749

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