CVE-2026-34988: Improper Restriction of Operations within the Bounds of a Memory Buffer

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 of resetting the...

PT-2026-31693

Name of the Vulnerable Software and Affected Versions Wasmtime versions prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1 Description Wasmtime's implementation of transcoding strings between components has a flaw where the return value of a guest component's realloc function is not validated before the...

WasmTime buffer error vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1 contained a buffer error vulnerability. This vulnerability stemmed from the lack of validation for the return value of the realloc function in guest...

PT-2026-31691

Name of the Vulnerable Software and Affected Versions Wasmtime versions 28.0.0 through 36.0.6, 42.0.2 and 43.0.1 Description Wasmtime's pooling allocator implementation contains a flaw where linear memory contents can leak between WebAssembly instances under specific configurations. This occurs d...

PT-2026-31688

Name of the Vulnerable Software and Affected Versions Wasmtime versions 32.0.0 through 36.0.6, 42.0.2, and 43.0.1 Description Wasmtime's Cranelift compilation backend has a flaw on aarch64 architectures when handling specific heap access patterns. This can lead to incorrect address calculations,...

WasmTime buffer error vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 36.0.7, 42.0.2, and 43.0.1 contained a buffer error vulnerability. This vulnerability stemmed from the pooled allocator using incorrect predicates when resetting virtual memory...

WasmTime security vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 36.0.7, 42.0.2, and 43.0.1 contained security vulnerabilities. These vulnerabilities were caused by an error in the Winch compiler backend, which incorrectly interpreted the table.grow...

CVE-2026-35186: Memory Allocation with Excessive Size Value

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 operator, internally i...

WasmTime has a vulnerability related to input validation.

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1 contained a vulnerability related to input validation errors. This vulnerability stemmed from the improper validation of the alignment of reallocated...

WasmTime buffer error vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions prior to 24.0.7, 36.0.7, 42.0.2, and 43.0.1 of Wastime contain a buffer error vulnerability. This vulnerability arises from incorrectly verifying the number of code units rather than the byte length when...

CVE-2026-34941: Out-of-bounds Read

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 performing a bounds chec...

CVE-2026-34942: Improper Validation of Array Index

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 pointers could be...

WasmTime buffer error vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 36.0.7, 42.0.2, and 43.0.1 contained a buffer error vulnerability. This vulnerability stemmed from errors in the Cranelift compilation backend when processing certain heap access...

PT-2026-31690

Name of the Vulnerable Software and Affected Versions Wasmtime versions 25.0.0 through 36.0.6, 42.0.2, and 43.0.1 Description Wasmtime, a runtime for WebAssembly, may allow guest WebAssembly code to access host memory outside of its designated sandbox when using the Winch compiler backend. This...

PT-2026-31692

Name of the Vulnerable Software and Affected Versions Wasmtime versions 25.0.0 through 36.0.6, 42.0.2, and 43.0.1 Description Wasmtime, a runtime for WebAssembly, has an issue in its Winch compiler backend where the translation of the table.grow operator results in an incorrect type. Specifically...

CVE-2026-34971: Out-of-bounds Read

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 bounds checks a...

CVE-2026-34943: Uncaught Exception

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 that these bits...

PT-2026-31686

Name of the Vulnerable Software and Affected Versions Wasmtime versions 25.0.0 through 36.0.6, 42.0.2, and 43.0.1 Description Wasmtime's Winch compiler has a flaw in how it handles the table.size instruction with 64-bit tables, part of the WebAssembly memory64 proposal. This can lead to the...

WasmTime security vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 25.0.0, 36.0.7, 42.0.2, and 43.0.1 contained security vulnerabilities. These vulnerabilities stemmed from the Winch compiler incorrectly translating the table.size instruction, which i...

tree-sitter-cli -- Always-Incorrect Control Flow Implementation in wasmtime crate

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-q49f-xg75-m9xw reports: 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 ...