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Findings

CVE-2026-27572

Wasmtime is a runtime for WebAssembly.

Published Feb 24, 2026 · updated Jun 17, 2026 · bytecodealliance wasmtime

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 resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the 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.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Feb 24, 2026 · NIST NVD

    Detected

    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 resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the crate is backed by a data structure which panics when it reaches excessive capacity and this condition was not handled gracefully in Wasmtime. Pa

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the crate is backed by a data structure which panics when it reaches excessive capacity and this condition was not handled gracefully in Wasmtime. Pa

Affected

  • cpe bytecodealliance/wasmtimeversion unspecified

Sources

  • NIST NVDVulnerability recordCVE-2026-27572

    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 resource is susceptible to panics when too many fields are added to the set of headers. Wasmtime's implementation in the

    nvd.nist.gov

References