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.
Published: 2026-10-02
Score: 2 Low
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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Remediation

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History

Fri, 02 Oct 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Bytecodealliance
Bytecodealliance wasmtime
Vendors & Products Bytecodealliance
Bytecodealliance wasmtime

Fri, 02 Oct 2026 18:00:00 +0000

Type Values Removed Values Added
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.
Title Wasmtime: Preemption and traps during bulk operations enable breaking internal VM state
Weaknesses CWE-362
References
Metrics cvssV4_0

{'score': 2, 'vector': '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'}


Subscriptions

Bytecodealliance Wasmtime
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-02T17:37:50.941Z

Reserved: 2026-10-02T14:38:43.244Z

Link: CVE-2026-104855

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-02T18:17:02.083

Modified: 2026-10-02T18:17:02.220

Link: CVE-2026-104855

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-02T19:30:17Z

Weaknesses
  • CWE-362

    Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')