CVE-2026-104855
LowCVSS 2.0Exploitation Probability (EPSS)
Low risk18th percentile - higher than 18% of all known CVEs
Summary
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. This can result in a crash, invalid memory access, or GC heap corruption.
Risk Assessment
Invalid intermediate state can lead to application crashes, invalid memory access, or GC heap corruption. This may be exploited to destabilize or potentially achieve code execution in Wasmtime embeddings with vulnerable callbacks.
Recommendation
Upgrade Wasmtime to version 46.0.2 or 47.0.3. Embeddings whose callbacks only access host data in Store<T> and that discard a Store after timeout or epoch deadline are not affected.
Other vulnerabilities in Wasmtime
See all- CVE-2026-58494Medium
Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.11, 36.0.12, 45.0.3, and 46.0.1, the wasmtime-wasi component checked directory permissions but not matching FilePerms on source and destination preopens during hard-link creation and renaming. This allowed a WASI guest with read-only source file capability to overwrite host files exposed as FilePerms::READ through wasip1, wasip2, or wasip3 filesystem interfaces.
- CVE-2026-54786Medium
Wasmtime prior to versions 24.0.10, 36.0.11, 44.0.3, and 45.0.2 contains a vulnerability in the native WASIp1 implementation where the fd_renumber function fails to properly close the target file descriptor. This causes resource leaks in the host system, potentially leading to exhaustion of file descriptors and resources.
- CVE-2026-47261High
Wasmtime, a runtime for WebAssembly, has a vulnerability in versions prior to 24.0.9, 36.0.10, and 44.0.2 that allows bypassing the access control mechanism using the wasip2 descriptor.open-at or wasip1 path_open interfaces. The issue arises from a missing assignment in the open mode handling, allowing files to be opened with the OpenFlags::TRUNCATE flag without the necessary write permissions.
- CVE-2026-44216High
Wasmtime versions 30.0.0 through 36.0.8, 43.0.2, and 44.0.1 contain a vulnerability where allocation logic for WebAssembly tables panics on overflow. This panic can be triggered when allocating extremely large tables (64-bit range via memory64 proposal). An attacker can cause a denial of service by providing a WebAssembly module or component that requests such a large table.
- CVE-2026-34971High
Wasmtime versions 32.0.0 through 36.0.7, 42.0.2, and 43.0.1 have a bug in the Cranelift compiler on aarch64 that miscalculates memory addresses during heap access. This allows WebAssembly modules to bypass bounds checks and access arbitrary host memory, resulting in a sandbox escape.
- CVE-2025-62711Low
Wasmtime, a runtime for WebAssembly, contains a vulnerability in versions from 38.0.0 to before 38.0.3. A bug in the implementation of component-model related host-to-wasm trampolines allows carefully crafting a component that, when called in a specific way, would crash the host with a segfault or assert failure. Wasmtime 38.0.3 has been released and is patched. There are no workarounds.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS