wasmtime has 77 CVEs on record between 2021 and 2026. Disclosure cadence is accelerating: 41 in the last 90 days against 2 in the 90 before. The busiest recent month was October 2026 with 35. The median CVSS is 5.3 (medium), with 3 rated critical. None have a confirmed exploitation report.

CVEs per month

Weakness classes

Products

Worst active — by depth score

wasmtime vulnerabilities

Mis-typed WebAssembly tag imports can lead to GC heap corruption

Rooting for GC values live across `try_call` may be missing, causing GC heap corruption

Wasmtime component async-lifted callback result count is unvalidated, causing a native stack buffer overflow

Rooting for GC values live across `try_call` may be missing, causing GC heap corruption

Mis-typed WebAssembly tag imports can lead to GC heap corruption

`call_ref` and exception `catch` can drop some fuel accounting, leading to exponential fuel amplification

Dynamic record lifting can allocate beyond the hostcall fuel limit

`call_ref` and exception `catch` can drop some fuel accounting, leading to exponential fuel amplification

Guest controlled-size host heap allocation through WASIp3 streams

Filesystem sandbox escape when paths or symlinks contain trailing slashes

Guest controlled-size host heap allocation through WASIp3 streams

Preemption and traps during bulk operations enable breaking internal VM state

Stores can mix up type indices between engines

Miscompiled guest heap access enables sandbox escape on aarch64 Cranelift

Improperly masked return value from `table.grow` with Winch compiler backend

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

Heap OOB read in component model UTF-16 to latin1+utf16 string transcoding

Out-of-bounds write or crash when transcoding component model strings

Use-after-free bug after cloning `wasmtime::Linker`

Panic when transcoding misaligned component model UTF-16 strings

Data leakage between pooling allocator instances

Host panic when Winch compiler executes `table.fill`

Wasmtime segfault or unused out-of-sandbox load with `f64x2.splat` operator on Cranelift x86-64

Host data leakage with 64-bit tables and Winch

Panic when lifting `flags` component value

Panic adding excessive fields to a `wasi:http/types.fields` instance

Guest-controlled resource exhaustion in WASI implementations

Panic when dropping a `[Typed]Func::call_async` future

Wasmtime segfault or unused out-of-sandbox load with `f64.copysign` operator on x86-64

Unsound API access to a WebAssembly shared linear memory