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OpenAdvisories
Medium · 6.9 CVE-2026-27572 EUVD-2026-8569GHSA-243v-98vx-264hRUSTSEC-2026-0021

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

Published Feb 24, 2026 · Updated Feb 27, 2026 · Assigned by GitHub_M

Description

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` crate is backed by a data structure which panics when it reaches excessive capacity and this condition was not handled gracefully in Wasmtime. Panicking in a WASI implementation is a Denial of Service vector for embedders and is treated as a security vulnerability in Wasmtime. Wasmtime 24.0.6, 36.0.6, 40.0.4, 41.0.4, and 42.0.0 patch this vulnerability and return a trap to the guest instead of panicking. There are no known workarounds at this time. Embedders are encouraged to update to a patched version of Wasmtime.

Affected products

VendorProductAffectedFixed
bytecodealliance wasmtime < 24.0.6, >= 25.0.0, < 36.0.6, >= 37.0.0, < 40.0.4, >= 41.0.0, < 41.0.4 —

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

ReleasePackageFixed inAdvisory
Debian 14 rust-wasmtime 36.0.6+dfsg-1 —
Debian 13 rust-wasmtime No fix yet —
ReleasePackageFixed inAdvisory
Ubuntu 26.10 rust-wasmtime No fix yet —
Ubuntu 26.04 LTS rust-wasmtime No fix yet —
Ubuntu 25.10 rust-wasmtime No fix yet —
Ubuntu 24.04 LTS rust-wasmtime No fix yet —

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling wash No fix yet —
Wolfi rolling wasmcloud 2.0.1-r0 —
Wolfi rolling wizer 10.0.0-r7 —
Wolfi rolling yara-x 1.13.0-r2 —
Wolfi rolling zed 0.228.0-r3 —
Wolfi rolling zellij 0.44.0-r0 —

Affected packages

EcosystemPackageAffectedFixedRecord
crates.io wasmtime < 24.0.6 24.0.6 GHSA-243v-98vx-264h
crates.io wasmtime >= 25.0.0, < 36.0.6 36.0.6 GHSA-243v-98vx-264h
crates.io wasmtime >= 37.0.0, < 40.0.4 40.0.4 GHSA-243v-98vx-264h
crates.io wasmtime >= 0.0.0-0, < 24.0.6 · >= 25.0.0, < 36.0.6 · >= 37.0.0, < 40.0.4 · >= 41.0.0, < 41.0.4 24.0.6, 36.0.6, 40.0.4, 41.0.4 RUSTSEC-2026-0021

References