VulnerabilityAnalyzed

CVE-2026-27572

Panicking in a WASI implementation is a Denial of Service vector for embedders and is treated as a security vulnerability in Wasmtime.

MEDIUM 6.9EPSS 0.47%

Does this matter?

Lower severity and a low EPSS score (0.47%). Track it; it rarely justifies an emergency change on its own.

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.

CVSS 4.0: 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.47% probability · 39th percentile
CISA KEV: Not listed
Weakness: CWE-770
Affected: bytecodealliance/wasmtime
Source: security-advisories@github.com

References

https://docs.rs/http/1.4.0/http/header/#limitationsNot Applicable
https://github.com/bytecodealliance/wasmtime/commit/301dc7162cca51def19131019af1187f45901c0aPatch
https://github.com/bytecodealliance/wasmtime/releases/tag/v24.0.6Product, Release Notes
https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.6Product, Release Notes
https://github.com/bytecodealliance/wasmtime/releases/tag/v40.0.4Product, Release Notes
https://github.com/bytecodealliance/wasmtime/releases/tag/v41.0.4Product, Release Notes
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-243v-98vx-264hThird Party Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.