Wasmtime is a runtime for WebAssembly. Prior to 36.0.19, 48.0.7, and 49.0.4, the Cranelift compiler backend on aarch64 can compile a Wasm br_table instruction with more than approximately 256,000 targets so that it has an incorrect conditional branch target. The branch can then j...
Product
bytecodealliance wasmtime vulnerabilities
45 published CVES affecting bytecodealliance wasmtime, from public sources (CVE.org, NVD, CISA KEV, FIRST EPSS, OSV).
- Total
- 45
- Critical
- 7
- High
- 7
- Medium
- 20
- Low
- 11
- Unscored
- 0
- CISA KEV
- 0
Latest bytecodealliance wasmtime CVEs
Newest publication first · page 1 of 2
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CriticalCVSS 9.9 EPSS 0.99%
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MediumCVSS 5.7 EPSS 0.43%
Wasmtime is a runtime for WebAssembly. From 46.0.0 until 48.0.7 and 49.0.4, lowering a host-created component-model stream or future into a guest can omit a required payload-type check after the value passes through guest code and returns through StreamAny, FutureAny, Val::Stream...
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CriticalCVSS 9.9 EPSS 0.45%
Wasmtime is a runtime for WebAssembly. Prior to 36.0.19 and 43.0.0, the Cranelift compiler backend bit-packs SSA value indices in a way that can silently overflow in release builds when compiling a sufficiently large or specially crafted Wasm function with many SSA values. The ov...
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LowCVSS 2.0 EPSS 0.28%
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_ca...
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MediumCVSS 6.5 EPSS 0.17%
Wasmtime is a runtime for WebAssembly. Prior to 24.0.11, 36.0.12, 45.0.3, and 46.0.1, wasmtime-wasi hard-link creation and renaming check directory permissions but not matching FilePerms on source and destination preopens, allowing a WASI guest with a read-only source file capabi...
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LowCVSS 2.3 EPSS 0.37%
Wasmtime is a runtime for WebAssembly. All versions prior to 24.0.10; versions 25.0.0 through those before 36.0.11; versions 37.0.0 through those before 44.0.3; and versions 45.0.0 and 45.0.1 contain a native implementation of WASIp1 which suffers from a leak in the fd_renumber f...
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CVE-2026-47261 Wasmtime: WASI path_open(TRUNCATE) bypasses `FilePerms::WRITE` host restriction
PublishedHighCVSS 7.5 EPSS 0.36%Wasmtime is a runtime for WebAssembly. In versions prior to 24.0.9, 36.0.10, and 44.0.2, when a filesystem preopen is given DirPerms::all() and FilePerms::READ without FilePerms::WRITE, this access control mechanism can be bypassed via the wasip2 descriptor.open-at or wasip1 path...
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MediumCVSS 5.9 EPSS 0.32%
Wasmtime is a runtime for WebAssembly. From 30.0.0 to 36.0.8, 43.0.2, and 44.0.1, Wasmtime's allocation logic for a WebAssembly table contained checked arithmetic which panicked on overflow. This overflow is possible to trigger, and thus panic, when a table with an extremely larg...
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CVE-2026-35195 Wasmtime has an out-of-bounds write or crash when transcoding component model strings
PublishedMediumCVSS 6.1 EPSS 0.22%Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings between components contains a bug where the return value of a guest component's realloc is not validated before the host attempts to write through...
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MediumCVSS 6.1 EPSS 0.22%
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler backend contains a bug where translating the table.grow operator causes the result to be incorrectly typed. For 32-bit tables this means that the result of the opera...
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LowCVSS 2.3 EPSS 0.30%
Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation...
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CriticalCVSS 9.0 EPSS 0.28%
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime with its Winch (baseline) non-default compiler backend may allow properly constructed guest Wasm to access host memory outside of its linear-memory sandbox. This vulnerability requir...
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LowCVSS 1.0 EPSS 0.12%
Wasmtime is a runtime for WebAssembly. In 43.0.0, cloning a wasmtime::Linker is unsound and can result in use-after-free bugs. This bug is not controllable by guest Wasm programs. It can only be triggered by a specific sequence of embedder API calls made by the host. Specifically...
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CVE-2026-34971 Wasmtime miscompiled guest heap access enables sandbox escape on aarch64 Cranelift
PublishedCriticalCVSS 9.0 EPSS 0.32%Wasmtime is a runtime for WebAssembly. From 32.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Cranelift compilation backend contains a bug on aarch64 when performing a certain shape of heap accesses which means that the wrong address is accessed. When combined with explicit...
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MediumCVSS 5.9 EPSS 0.37%
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on...
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LowCVSS 2.3 EPSS 0.34%
Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a bug where a 64-bit table, part of the memory64 proposal of WebAssembly, incorrectly translated the table.size instruction. This bug could lead to disclosi...
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CVE-2026-34944 Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on x86-64
PublishedMediumCVSS 4.1 EPSS 0.24%Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, On x86-64 platforms with SSE3 disabled Wasmtime's compilation of the f64x2.splat WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals-based-traps are disabl...
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MediumCVSS 5.6 EPSS 0.34%
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime contains a possible panic which can happen when a flags-typed component model value is lifted with the Val type. If bits are set outside of the set of flags the component model specifies...
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MediumCVSS 5.9 EPSS 0.37%
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of transcoding strings into the Component Model's utf16 or latin1+utf16 encodings improperly verified the alignment of reallocated strings. This meant that unaligned poin...
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MediumCVSS 6.9 EPSS 0.39%
Wasmtime is a runtime for WebAssembly. Prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1, Wasmtime contains a vulnerability where when transcoding a UTF-16 string to the latin1+utf16 component-model encoding it would incorrectly validate the byte length of the input string when perform...
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MediumCVSS 6.9 EPSS 0.52%
Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.6, 36.0.6, 4.0.04, 41.0.4, and 42.0.0, Wasmtime's implementation of the wasi:http/types.fields resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the wa...
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CVE-2026-27204 Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion
PublishedMediumCVSS 6.9 EPSS 0.40%Wasmtime is a runtime for WebAssembly. Prior to versions 24.0.6, 36.0.6, 4.0.04, 41.0.4, and 42.0.0, Wasmtime's implementation of WASI host interfaces are susceptible to guest-controlled resource exhaustion on the host. Wasmtime did not appropriately place limits on resource allo...
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CVE-2026-27195 Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future
PublishedMediumCVSS 6.9 EPSS 0.41%Wasmtime is a runtime for WebAssembly. Starting with Wasmtime 39.0.0, the component-model-async feature became the default, which brought with it a new implementation of [Typed]Func::call_async which made it capable of calling async-typed guest export functions. However, that imp...
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CVE-2026-24116 Wasmtime segfault or unused out-of-sandbox load with f64.copysign operator on x86-64
PublishedMediumCVSS 4.1 EPSS 0.24%Wasmtime is a runtime for WebAssembly. Starting in version 29.0.0 and prior to version 36.0.5, 40.0.3, and 41.0.1, on x86-64 platforms with AVX, Wasmtime's compilation of the f64.copysign WebAssembly instruction with Cranelift may load 8 more bytes than is necessary. When signals...
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LowCVSS 1.8 EPSS 0.12%
Wasmtime is a runtime for WebAssembly. Prior to version 38.0.4, 37.0.3, 36.0.3, and 24.0.5, Wasmtime's Rust embedder API contains an unsound interaction where a WebAssembly shared linear memory could be viewed as a type which provides safe access to the host (Rust) to the content...
Sources: CVE.org, NVD, CISA KEV, FIRST EPSS, OSV and public exploit-reference metadata. Product matching comes from the published CVE records. A proof-of-concept means public code exists; it is not evidence of exploitation.