{"id":"JLSEC-2026-1353","summary":"Wasmtime can panic when adding excessive fields to a `wasi:http/types.fields` instance","details":"### Impact\n\nWasmtime'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.\n\n### Patches\n\nWasmtime 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.\n\n### Workarounds\n\nThere are no known workarounds at this time, embedders are encouraged to update to a patched version of Wasmtime.\n\n### Resources\n\n  - [Limitations of `http::HeaderMap`](https://docs.rs/http/1.4.0/http/header/#limitations)","modified":"2026-08-21T21:14:20.644203302Z","published":"2026-08-21T20:43:33.133Z","upstream":["CVE-2026-27572","EUVD-2026-8569","GHSA-243v-98vx-264h"],"database_specific":{"sources":[{"id":"CVE-2026-27572","imported":"2026-08-21T20:09:02.075Z","modified":"2026-06-17T10:27:19.773Z","published":"2026-02-24T22:16:32.687Z","url":"https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27572","html_url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27572","database_specific":{"status":"Analyzed"},"affected":{"bytecodealliance:wasmtime":["\u003c 24.0.6","\u003e= 25.0.0, \u003c 36.0.6","\u003e= 37.0.0, \u003c 40.0.4","\u003e= 41.0.0, \u003c 41.0.4"]}},{"imported":"2026-08-21T20:09:07.458Z","modified":"2026-02-27T20:25:49Z","published":"2026-02-24T21:08:06Z","url":"https://api.github.com/advisories/GHSA-243v-98vx-264h","html_url":"https://github.com/advisories/GHSA-243v-98vx-264h","id":"GHSA-243v-98vx-264h"},{"modified":"2026-02-27T20:55:29Z","published":"2026-02-24T21:31:50Z","url":"https://euvdservices.enisa.europa.eu/api/enisaid?id=EUVD-2026-8569","html_url":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-8569","affected":{"bytecodealliance:wasmtime":["25.0.0, \u003c 36.0.6","37.0.0, \u003c 40.0.4","41.0.0, \u003c 41.0.4","\u003c 24.0.6"]},"id":"EUVD-2026-8569","imported":"2026-08-21T20:09:03.524Z"}],"license":"CC-BY-4.0"},"references":[{"type":"WEB","url":"https://docs.rs/http/1.4.0/http/header/#limitations"},{"type":"WEB","url":"https://github.com/advisories/GHSA-243v-98vx-264h"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/commit/301dc7162cca51def19131019af1187f45901c0a"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v24.0.6"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v36.0.6"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v40.0.4"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/releases/tag/v41.0.4"},{"type":"WEB","url":"https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-243v-98vx-264h"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27572"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2026-0021.html"}],"affected":[{"package":{"name":"Wasmtime_jll","ecosystem":"Julia","purl":"pkg:julia/Wasmtime_jll?uuid=d20e7296-4f3e-515c-90b9-d2595a77bf72"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"45.0.1+0"}]}],"database_specific":{"source":"https://github.com/JuliaLang/SecurityAdvisories.jl/tree/generated/osv/2026/JLSEC-2026-1353.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V4","score":"CVSS: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/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}],"credits":[{"name":"alexcrichton","contact":["https://github.com/alexcrichton"],"type":"OTHER"}]}