{"id":"CVE-2026-119134","kind":"vulnerability","aliases":["CVE-2026-119134"],"related":[],"title":"Wasmtime: guest code can exhaust host memory via resource handles","description":"Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 caps component-model resource handle tables only per component instance and does not charge handle allocations to any ResourceLimiter or StoreLimits. A malicious guest can repeatedly call resource.new and instantiate sub-components to exceed the per-instance cap many times over, causing unbounded host memory growth.","summary":"Wasmtime, the WebAssembly runtime, does not count component-model resource handles against the store's memory limits, so a malicious guest can repeatedly create resources and sub-components. This makes host memory grow without bound, which can crash the host process.","severity":"medium","cvss":6.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["runtime","rust","wasmtime","webassembly"],"not_affected_if":["no-component-model","trusted-guests-only"],"how_to_check":null,"fix":"- Wasmtime `36.0.18`\n- Wasmtime `48.0.6`\n- Wasmtime `49.0.3`","status":"open","published_at":"2026-10-29T16:18:06+00:00","first_seen_at":"2026-10-29T16:25:58+00:00","triaged_at":"2026-10-29T16:30:09+00:00","updated_at":"2026-10-29T16:30:09+00:00","category":"runtime","confidence":0.6,"triage":{"at":"2026-10-29T16:30:09Z","model":"claude-haiku-5-5","output":{"fix":"- Wasmtime `36.0.18`\n- Wasmtime `48.0.6`\n- Wasmtime `49.0.3`","reach":"unknown","title":"Wasmtime: guest code can exhaust host memory via resource handles","impact":"medium","summary":"Wasmtime, the WebAssembly runtime, does not count component-model resource handles against the store's memory limits, so a malicious guest can repeatedly create resources and sub-components. This makes host memory grow without bound, which can crash the host process.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["wasmtime","webassembly","rust"],"confidence":0.6,"fix_status":"available","needs_auth":"unknown","worst_case":"Untrusted guest exhausts host memory and crashes the process","analyst_note":"","how_to_check":"- Check the Wasmtime version in your dependencies, for example `wasmtime --version` or the `wasmtime` entry in Cargo.lock.\n- Flag any build using a version before `36.0.18`, `37.0.0` through `48.0.5`, or `49.0.0` through `49.0.2`.\n- Note whether you run untrusted WebAssembly components with the component model enabled.","plain_action":"","needs_analyst":false,"not_affected_if":["trusted-guests-only","no-component-model"],"who_is_affected":"Teams that embed Wasmtime to run WebAssembly components supplied by untrusted users or third parties are exposed, because a guest can drive host memory use upward. Applications running only trusted, first-party WebAssembly, or not using the component model, are less exposed. unknown whether the sources list any further configuration conditions.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"medium"},"cost_usd":0.000727,"input_tokens":4187,"output_tokens":616,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-119134':13A,16A '-2026':12A,15A '36.0.18':66C '37.0.0':67C '48.0.6':69C '49.0.0':71C '49.0.3':73C 'alloc':90C 'bound':57B 'call':101C 'cap':74C,114C 'caus':118C 'charg':88C 'code':3A 'compon':29B,50B,76C,83C,107C 'component-model':28B,75C 'count':27B 'crash':60B 'creat':45B 'cve':11A,14A 'exceed':109C 'exhaust':5A 'grow':55B 'growth':122C 'guest':2A,42B,98C 'handl':10A,32B,79C,89C 'host':6A,53B,62B,120C 'instanc':84C,113C 'instanti':104C 'limit':38B 'make':52B 'malici':41B,97C 'mani':115C 'memori':7A,37B,54B,121C 'model':30B,77C 'per':82C,112C 'per-inst':111C 'process':63B 'repeat':44B,100C 'resourc':9A,31B,46B,78C 'resource.new':102C 'resourcelimit':93C 'runtim':17B,24B 'rust':18B 'store':35B 'storelimit':95C 'sub':49B,106C 'sub-compon':48B,105C 'tabl':80C 'time':116C 'unbound':119C 'via':8A 'wasmtim':1A,19B,21B,64C 'webassembl':20B,23B 'without':56B","nicknames":[],"mitigations":[],"who_affected":"Teams that embed Wasmtime to run WebAssembly components supplied by untrusted users or third parties are exposed, because a guest can drive host memory use upward. Applications running only trusted, first-party WebAssembly, or not using the component model, are less exposed. unknown whether the sources list any further configuration conditions.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"first_public_at":"2026-10-29T16:18:06+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/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-2026-119134","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119134","severity":null,"published_at":"2026-10-29T16:18:06+00:00","modified_at":"2026-10-29T16:18:06+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"}