{"id":"CVE-2026-119143","kind":"vulnerability","aliases":["CVE-2026-119143"],"related":[],"title":"Wasmtime: zero-length stream operations let guest code crash the host","description":"Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 contains a denial of service vulnerability that allows guest code to trigger a host panic through out-of-bounds zero-length stream operations. Malicious guests can perform zero-length component model stream reads or writes with unvalidated addresses, causing Direct{Source,Destination}::remaining to panic and crash WASIp3 embedders.","summary":"Wasmtime is a WebAssembly runtime. Guest code can send zero-length component model stream reads or writes with unvalidated addresses, which makes the host panic and crash WASIp3 embedders.","severity":"medium","cvss":5.9,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["runtime","rust","wasip3","wasmtime","webassembly"],"not_affected_if":["pre-wasip3-embedding","trusted-guests-only"],"how_to_check":"- Check the Wasmtime version in the embedding application's dependency lockfile, for example `wasmtime` in `Cargo.lock`\n- Look for WASIp3 component model stream support enabled in the host application","fix":"- Move to `48.0.6` on the 48 line\n- Move to `49.0.3` on 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":"2026-10-29T16:31:36+00:00","updated_at":"2026-10-29T16:31:36+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-29T16:31:36Z","model":"claude-haiku-5-5","output":{"fix":"- Move to `48.0.6` on the 48 line\n- Move to `49.0.3` on the 49 line","reach":"unknown","title":"Wasmtime: zero-length stream operations let guest code crash the host","impact":"low","summary":"Wasmtime is a WebAssembly runtime. Guest code can send zero-length component model stream reads or writes with unvalidated addresses, which makes the host panic and crash WASIp3 embedders.","audience":"businesses","category":"runtime","nicknames":[],"who_cares":["wasmtime","webassembly","wasip3","rust"],"confidence":0.7,"fix_status":"available","needs_auth":"unknown","worst_case":"Guest code crashes the host process, causing denial of service","analyst_note":"","how_to_check":"- Check the Wasmtime version in the embedding application's dependency lockfile, for example `wasmtime` in `Cargo.lock`\n- Look for WASIp3 component model stream support enabled in the host application","plain_action":"","needs_analyst":false,"not_affected_if":["trusted-guests-only","pre-wasip3-embedding"],"who_is_affected":"Applications that embed Wasmtime 46.0.0 before 48.0.6 or 49.0.0 before 49.0.3 and run untrusted WebAssembly guests using WASIp3 component model streams are exposed to a host crash. Teams running only trusted guests, or versions outside these ranges, can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000689,"input_tokens":4188,"output_tokens":541,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-119143':15A,18A '-2026':14A,17A '46.0.0':55C '48.0.6':57C '49.0.0':59C '49.0.3':61C 'address':44B,102C 'allow':69C 'bound':81C 'caus':103C 'code':9A,30B,71C 'compon':36B,94C 'contain':62C 'crash':10A,51B,111C 'cve':13A,16A 'denial':64C 'destin':106C 'direct':104C 'embedd':53B,113C 'guest':8A,29B,70C,88C 'host':12A,48B,75C 'length':4A,35B,84C,93C 'let':7A 'make':46B 'malici':87C 'model':37B,95C 'oper':6A,86C 'out-of-bound':78C 'panic':49B,76C,109C 'perform':90C 'read':39B,97C 'remain':107C 'runtim':19B,28B 'rust':20B 'send':32B 'servic':66C 'sourc':105C 'stream':5A,38B,85C,96C 'trigger':73C 'unvalid':43B,101C 'vulner':67C 'wasip3':21B,52B,112C 'wasmtim':1A,22B,24B,54C 'webassembl':23B,27B 'write':41B,99C 'zero':3A,34B,83C,92C 'zero-length':2A,33B,82C,91C","nicknames":[],"mitigations":[],"who_affected":"Applications that embed Wasmtime 46.0.0 before 48.0.6 or 49.0.0 before 49.0.3 and run untrusted WebAssembly guests using WASIp3 component model streams are exposed to a host crash. Teams running only trusted guests, or versions outside these ranges, can skip it.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"first_public_at":"2026-10-29T16:18:07+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-2026-119143","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-119143","severity":null,"published_at":"2026-10-29T16:18:07+00:00","modified_at":"2026-10-29T16:18:08+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"}