GHSA-XX5W-CVP6-JV83 Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access

Impact 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 requires use of the Winch compiler -Ccompiler=winch. By default, Wasmtime uses its Cranelift backend, not...

EUVD-2026-21031

Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access...

Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access

Impact 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 requires use of the Winch compiler -Ccompiler=winch. By default, Wasmtime uses its Cranelift backend, not...

CVE-2026-34971

A flaw was found in Wasmtime, a runtime for WebAssembly. On aarch64 systems, a miscompilation bug in Wasmtime's Cranelift backend can be exploited by a guest WebAssembly module. This vulnerability allows the module to bypass memory bounds checks, enabling arbitrary read and write operations on th...

CVE-2026-35186

A flaw was found in Wasmtime, a runtime for WebAssembly. The Winch compiler backend incorrectly handles the table.grow operator, leading to an internal type mismatch. This can result in a Denial of Service DoS, where the host process crashes. Additionally, under specific configurations with...

CVE-2026-34988

A flaw was found in Wasmtime, a runtime for WebAssembly. When Wasmtime's pooling allocator is configured with specific settings, it fails to properly reset virtual memory permissions. This oversight allows a malicious WebAssembly instance to read sensitive data from the linear memory of a...

CVE-2026-34945

A flaw was found in Wasmtime's Winch compiler. This vulnerability, present in versions from 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, arises from an incorrect translation of the table.size instruction for 64-bit WebAssembly tables. An attacker, by crafting a malicious WebAssembly guest, could...

CVE-2026-34943

A flaw was found in Wasmtime, a runtime for WebAssembly. A malicious guest can exploit an issue where a flags-typed component model value, containing unexpected bit settings, causes the host system to panic during processing. This vulnerability can lead to a Denial of Service DoS, rendering the...

CVE-2026-34944

A flaw was found in Wasmtime, a runtime for WebAssembly. On x86-64 platforms with SSE3 disabled, Wasmtime's Cranelift compiler backend may load additional data beyond the intended memory boundary when compiling the 'f64x2.splat' WebAssembly instruction. This out-of-bounds read can lead to a Denia...

CVE-2026-34942

A flaw was found in Wasmtime, a runtime for WebAssembly. This vulnerability allows a malicious guest to trigger a host panic by improperly verifying the alignment of reallocated strings during transcoding. By transferring specific strings across components, an attacker can exploit this to cause a...

CVE-2026-35195

A flaw was found in Wasmtime, a runtime for WebAssembly. A malicious guest component can exploit an issue where the host does not validate memory allocation requests. This allows the guest to write arbitrary data to locations outside its designated memory. Depending on the configuration, this cou...

CVE-2026-34941

A flaw was found in Wasmtime, a runtime for WebAssembly. When transcoding a UTF-16 string to the latin1+utf16 component-model encoding, Wasmtime incorrectly validates the byte length of the input string, checking the number of code units instead of the actual byte length. This vulnerability can...

CVE-2026-34983

A flaw was found in Wasmtime, a runtime for WebAssembly. This vulnerability allows for a use-after-free condition when a host application incorrectly clones and then drops a wasmtime::Linker instance before its cloned counterpart is used. This can lead to unpredictable program behavior and...

CVE-2026-34987

A flaw was found in Wasmtime, a runtime for WebAssembly. When using its non-default Winch compiler backend, a properly constructed guest WebAssembly Wasm module can exploit an incorrect assumption in how memory offsets are handled. This allows the guest Wasm to access host memory outside its...

EUVD-2026-21039

Wasmtime has out-of-bounds write or crash when transcoding component model strings...

GHSA-394W-HWHG-8VGM Wasmtime has out-of-bounds write or crash when transcoding component model strings

Impact 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 the pointer. This enables a guest to cause the host to write arbitrary transcoded string bytes...

Wasmtime has out-of-bounds write or crash when transcoding component model strings

Impact 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 the pointer. This enables a guest to cause the host to write arbitrary transcoded string bytes...

GHSA-6WGR-89RJ-399P Wasmtime has data leakage between pooling allocator instances

Impact 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 of resetting the virtual memory permissions for linear memory used the wrong predicate to determin...

EUVD-2026-21033

Wasmtime has data leakage between pooling allocator instances...

Wasmtime has data leakage between pooling allocator instances

Impact 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 of resetting the virtual memory permissions for linear memory used the wrong predicate to determin...