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CVE-2026-104855— Wasmtime: Preemption and traps during bulk operations enable breaking internal VM state

Quick assessment

Affected
bytecodealliance wasmtime
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.

Wasmtime 是 WebAssembly 的运行时环境。在版本 46.0.0 至 46.0.2 以及 47.0.3 之前，包含 、 和 等批量操作中的燃料（fuel）消耗检查和 epoch 抢占检查，可能会在嵌入器（embedder）在 中修改 ，或在取消操作或陷阱（trap）发生后继续使用 时，暴露出无效的中间状态。 具体而言： 被取消的不可为空（non-nullable）表的扩容操作可能留下空元素； 期间的线性内存扩容可能使保留的原始指针失效； 过程中由回调触发的垃圾回收（GC）可能使 GC 指针失效。 这

CVSS 2.0 · Low

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 2

VendorProduct Version RangeStatus
bytecodealliance wasmtime >= 46.0.0, < 46.0.2 affected
>= 47.0.0, < 47.0.3 affected
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I. Basic Information for CVE-2026-104855

Vulnerability Information
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Vulnerability Title
Wasmtime: Preemption and traps during bulk operations enable breaking internal VM state
Source: CVE Program / CVE List V5
Vulnerability Description
Wasmtime is a runtime for WebAssembly. From 46.0.0 until 46.0.2 and 47.0.3, fuel and epoch preemption checks inside bulk operations including memory.copy, table.grow, and array.copy can expose invalid intermediate state when an embedder mutates a Store in Store::epoch_deadline_callback or continues using a Store after cancellation or a trap. A cancelled non-nullable table growth can leave null elements, linear-memory growth during memory.copy can invalidate retained raw pointers, and callback-triggered garbage collection during array.copy can invalidate GC pointers, resulting in a crash, invalid memory access, or GC heap corruption. Embeddings whose callbacks only access the host data in Store<T>, and embeddings that discard a Store after timeout or epoch deadline, are not affected. This issue is fixed in versions 46.0.2 and 47.0.3.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
使用共享资源的并发执行不恰当同步问题(竞争条件)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
bytecodealliance wasmtime >= 46.0.0, < 46.0.2 -

II. Public POCs for CVE-2026-104855

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III. Intelligence Information for CVE-2026-104855

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Patches & Fixes for CVE-2026-104855 (3)

Vendor Advisories for CVE-2026-104855 (1)

Vendor Pages for CVE-2026-104855 (2)

IV. Related Vulnerabilities

Same product: wasmtime
Same vendor: bytecodealliance
Same weakness: CWE-362

V. Comments for CVE-2026-104855

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