{"id":"CVE-2026-115382","kind":"vulnerability","aliases":["CVE-2026-115382"],"related":[],"title":"Wasmtime: zero between-bytes timeout lets a guest crash the host","description":"Wasmtime 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 contains a denial-of-service vulnerability in its wasi:http implementation that allows guests to panic the host. Guests can specify a zero between-bytes-timeout request option, which is forwarded directly to a Tokio API that panics, crashing the host embedding.","summary":"Wasmtime versions 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 pass a guest-supplied zero between-bytes-timeout in wasi:http straight to a Tokio API that panics. A guest module can therefore crash the host process that embeds Wasmtime.","severity":"medium","cvss":5.9,"epss":0.00226,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["runtime","rust","wasi","wasmtime","webassembly"],"not_affected_if":["untrusted-guests-absent","version-outside-range","wasi-http-disabled"],"how_to_check":"- Run `wasmtime --version` on the host, or check the embedding application's pinned `wasmtime` crate version in Cargo.lock.\n- Confirm whether the application enables wasi:http and runs untrusted guest modules.","fix":"- Upgrade Wasmtime to `48.0.4` or later on the 48 line, or to `49.0.2` or later on the 49 line.\n- Rebuild and redeploy the embedding application after upgrading.","status":"open","published_at":"2026-10-22T19:17:45+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","triaged_at":"2026-10-25T04:07:58+00:00","updated_at":"2026-10-25T04:07:58+00:00","category":"runtime","confidence":0.8,"triage":{"at":"2026-10-25T04:07:58Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Wasmtime to `48.0.4` or later on the 48 line, or to `49.0.2` or later on the 49 line.\n- Rebuild and redeploy the embedding application after upgrading.","reach":"unknown","title":"Wasmtime: zero between-bytes timeout lets a guest crash the host","impact":"medium","summary":"Wasmtime versions 46.0.0 before 48.0.4 and 49.0.0 before 49.0.2 pass a guest-supplied zero between-bytes-timeout in wasi:http straight to a Tokio API that panics. A guest module can therefore crash the host process that embeds Wasmtime.","category":"runtime","nicknames":[],"who_cares":["wasmtime","wasi","webassembly","rust"],"confidence":0.8,"needs_auth":"unknown","worst_case":"A guest module crashes the entire host process.","analyst_note":"","how_to_check":"- Run `wasmtime --version` on the host, or check the embedding application's pinned `wasmtime` crate version in Cargo.lock.\n- Confirm whether the application enables wasi:http and runs untrusted guest modules.","needs_analyst":false,"not_affected_if":["untrusted-guests-absent","wasi-http-disabled","version-outside-range"],"who_is_affected":"Teams that embed Wasmtime and expose the wasi:http implementation to guest code they do not fully trust, such as plugin or multi-tenant hosts. Standalone uses of Wasmtime that run only trusted modules, or that do not enable wasi:http, are less exposed.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000634,"input_tokens":3400,"output_tokens":588,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-115382':15A,18A '-2026':14A,17A '46.0.0':26B,66C '48.0.4':28B,68C '49.0.0':30B,70C '49.0.2':32B,72C 'allow':86C 'api':50B,110C 'between-byt':3A 'between-bytes-timeout':39B,97C 'byte':5A,41B,99C 'contain':73C 'crash':10A,58B,113C 'cve':13A,16A 'denial':76C 'denial-of-servic':75C 'direct':106C 'emb':63B 'embed':116C 'forward':105C 'guest':9A,36B,54B,87C,92C 'guest-suppli':35B 'host':12A,60B,91C,115C 'http':45B,83C 'implement':84C 'let':7A 'modul':55B 'option':102C 'panic':52B,89C,112C 'pass':33B 'process':61B 'request':101C 'runtim':19B 'rust':20B 'servic':78C 'specifi':94C 'straight':46B 'suppli':37B 'therefor':57B 'timeout':6A,42B,100C 'tokio':49B,109C 'version':25B 'vulner':79C 'wasi':21B,44B,82C 'wasmtim':1A,22B,24B,64B,65C 'webassembl':23B 'zero':2A,38B,96C","nicknames":[],"mitigations":[],"who_affected":"Teams that embed Wasmtime and expose the wasi:http implementation to guest code they do not fully trust, such as plugin or multi-tenant hosts. Standalone uses of Wasmtime that run only trusted modules, or that do not enable wasi:http, are less exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T19:17:45+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-115382","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-115382","severity":null,"published_at":"2026-10-22T19:17:45+00:00","modified_at":"2026-10-23T15:17:29+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","fetched_at":"2026-10-23T22:29:02+00:00","note":null},{"source":"epss","external_id":"CVE-2026-115382","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-115382","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T07:15:51+00:00","fetched_at":"2026-10-24T07:15:51+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}