CVE-2026-27195

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 TypedFunc::callasync which made it capable of calling async-typed guest export functions. However, that implementation had a bu...

CVE-2026-27195

CVE-2026-27195 affects Wasmtime in versions where component-model-async is default (from 39.0.0). The bug causes a panic when a host embeds calls to wasmtime::component::[Typed]Func::call_async, drops the returned Future after polling, and then reuses the same component instance before the first ...

CVE-2026-27195 Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future

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 TypedFunc::callasync which made it capable of calling async-typed guest export functions. However, that implementation had a bu...

Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance

Impact 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 wasmtime-wasi-http crate is backed by a data structure which panics when it reaches excessive capacity and this...

GHSA-243V-98VX-264H Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance

Impact 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 wasmtime-wasi-http crate is backed by a data structure which panics when it reaches excessive capacity and this...

GHSA-852M-CVVP-9P4W Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion

Impact 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 allocations requested by the guests. This serves as a Denial of Service vector where a guest can induce a range of...

Wasmtime WASI implementations are vulnerable to guest-controlled resource exhaustion

Impact 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 allocations requested by the guests. This serves as a Denial of Service vector where a guest can induce a range of...

Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future

The affected versions of Wasmtime can panic if the host embedder drops the future returned by wasmtime::component::TypedFunc::callasync before it resolves. Details Starting with Wasmtime 39.0.0, the component-model-async feature became the default, which brought with it a new implementation of...

GHSA-XJHV-V822-PF94 Wasmtime is vulnerable to panic when dropping a `[Typed]Func::call_async` future

The affected versions of Wasmtime can panic if the host embedder drops the future returned by wasmtime::component::TypedFunc::callasync before it resolves. Details Starting with Wasmtime 39.0.0, the component-model-async feature became the default, which brought with it a new implementation of...

RUSTSEC-2026-0021 Panic adding excessive fields to a `wasi:http/types.fields` instance

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-243v-98vx-264h For more information see the GitHub-hosted security advisory...

RUSTSEC-2026-0020 Guest-controlled resource exhaustion in WASI implementations

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-852m-cvvp-9p4w For more information see the GitHub-hosted security advisory...

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

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-243v-98vx-264h For more information see the GitHub-hosted security advisory...

Guest-controlled resource exhaustion in WASI implementations

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-852m-cvvp-9p4w For more information see the GitHub-hosted security advisory...

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

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-xjhv-v822-pf94 For more information see the GitHub-hosted security advisory...

RUSTSEC-2026-0022 Panic when dropping a `[Typed]Func::call_async` future

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-xjhv-v822-pf94 For more information see the GitHub-hosted security advisory...

CVE-2026-27572: Allocation of Resources Without Limits or Throttling

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 wasmtime-wasi-http...

CVE-2026-27195: Improper Handling of Exceptional Conditions

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 TypedFunc::callasync which made it capable of calling async-typed guest export functions. However, that implementation had a bu...

WasmTime security vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. There is a security vulnerability in Wastime, which stems from a defect in the implementation of TypedFunc::callasync when the component-model-async feature is enabled by default. This could lead to a kernel crash...

WasmTime security vulnerability

Wasmtime is a lightweight WebAssembly runtime open source by the Bytecode Alliance. Versions of Wastime prior to 24.0.6, 36.0.6, 4.0.04, 41.0.4, and 42.0.0 contain security vulnerabilities. These vulnerabilities stem from the wasi:http/types Fields resource implementation, where excessive header...

PT-2026-21804

Name of the Vulnerable Software and Affected Versions Wasmtime versions 39.0.0 through 41.0.3 Description Wasmtime, a runtime for WebAssembly, can experience a panic when the host embedder drops the future returned by wasmtime::component::TypedFunc::call async before it resolves, and then calls t...