{"id":"CVE-2026-119139","kind":"vulnerability","aliases":["CVE-2026-119139"],"related":[],"title":"Wasmtime: leftover assertion lets a crafted component crash the host","description":"Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a leftover assertion in component::Func::call that rejects guest exports using the async ABI option. An attacker who supplies a component with an async-lifted export can crash the host process when an embedder invokes that export through Func::call.","summary":"Wasmtime, a WebAssembly runtime, contains a leftover assertion in component::Func::call that rejects guest exports using the async ABI option. An attacker who supplies a component with an async-lifted export can crash the host process when an embedder calls that export through Func::call.","severity":"medium","cvss":5.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["runtime","rust","wasmtime","webassembly"],"not_affected_if":["no-component-model","trusted-components-only"],"how_to_check":"- Check the Wasmtime version in the project's lockfile or Cargo.toml: `wasmtime` 46.0.0 before 48.0.6 or 49.0.0 before 49.0.3 is affected.\n- Look for embedders that call `Func::call` on component exports while loading untrusted or third-party WebAssembly components.","fix":"- Wasmtime `48.0.6` or later for the 46/48 line\n- Wasmtime `49.0.3` or later for the 49 line","status":"open","published_at":"2026-10-29T16:18:07+00:00","first_seen_at":"2026-10-29T16:25:58+00:00","triaged_at":"2026-10-29T16:31:38+00:00","updated_at":"2026-10-29T16:31:38+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-29T16:31:38Z","model":"claude-haiku-5-5","output":{"fix":"- Wasmtime `48.0.6` or later for the 46/48 line\n- Wasmtime `49.0.3` or later for the 49 line","reach":"unknown","title":"Wasmtime: leftover assertion lets a crafted component crash the host","impact":"low","summary":"Wasmtime, a WebAssembly runtime, contains a leftover assertion in component::Func::call that rejects guest exports using the async ABI option. An attacker who supplies a component with an async-lifted export can crash the host process when an embedder calls that export through Func::call.","audience":"developers","category":"runtime","nicknames":[],"who_cares":["wasmtime","webassembly","rust"],"confidence":0.7,"fix_status":"available","needs_auth":"no","worst_case":"Host process crashes when an untrusted component is invoked","analyst_note":"","how_to_check":"- Check the Wasmtime version in the project's lockfile or Cargo.toml: `wasmtime` 46.0.0 before 48.0.6 or 49.0.0 before 49.0.3 is affected.\n- Look for embedders that call `Func::call` on component exports while loading untrusted or third-party WebAssembly components.","plain_action":"","needs_analyst":false,"not_affected_if":["trusted-components-only","no-component-model"],"who_is_affected":"Applications that embed Wasmtime and load WebAssembly components from sources they do not fully control, then invoke an export through Func::call. Hosts that only run their own trusted components, or that do not use the component model's Func::call path, are less exposed. The sources do not say whether any default configuration triggers the assertion.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000714,"input_tokens":4152,"output_tokens":597,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-119139':13A,16A '-2026':12A,15A '46.0.0':69C '48.0.6':71C '49.0.0':73C '49.0.3':75C 'abi':40B,91C 'assert':3A,28B,79C 'async':39B,51B,90C,102C 'async-lift':50B,101C 'attack':43B,94C 'call':32B,62B,67B,83C,118C 'compon':7A,30B,47B,81C,98C 'contain':25B,76C 'craft':6A 'crash':8A,55B,106C 'cve':11A,14A 'embedd':61B,112C 'export':36B,53B,64B,87C,104C,115C 'func':31B,66B,82C,117C 'guest':35B,86C 'host':10A,57B,108C 'invok':113C 'leftov':2A,27B,78C 'let':4A 'lift':52B,103C 'option':41B,92C 'process':58B,109C 'reject':34B,85C 'runtim':17B,24B 'rust':18B 'suppli':45B,96C 'use':37B,88C 'wasmtim':1A,19B,21B,68C 'webassembl':20B,23B","nicknames":[],"mitigations":[],"who_affected":"Applications that embed Wasmtime and load WebAssembly components from sources they do not fully control, then invoke an export through Func::call. Hosts that only run their own trusted components, or that do not use the component model's Func::call path, are less exposed. The sources do not say whether any default configuration triggers the assertion.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"first_public_at":"2026-10-29T16:18:07+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:H/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-2026-119139","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119139","severity":null,"published_at":"2026-10-29T16:18:07+00:00","modified_at":"2026-10-29T16:18:07+00:00","first_seen_at":"2026-10-29T16:25:58+00:00","fetched_at":"2026-10-29T16:25:58+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"}