{"id":"CVE-2026-115380","kind":"vulnerability","aliases":["CVE-2026-115380"],"related":[],"title":"Wasmtime: WASI poll_oneoff lets guest modules stall the host","description":"Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains a denial of service vulnerability in the wasmtime-wasi WASI preview 0 poll_oneoff adapter, which performs O(n) host work per subscription without consuming or checking fuel. Malicious guest modules can pass many subscriptions to force long-running host computation that ignores configured fuel limits.","summary":"Wasmtime's WASI preview 0 poll_oneoff adapter does linear host work per subscription without charging fuel. A malicious guest module can pass many subscriptions and force long host computation that ignores configured fuel limits.","severity":"medium","cvss":5.1,"epss":0.00118,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["plugin-systems","runtime","self-hosted","wasi","wasmtime","webassembly"],"not_affected_if":["no-wasi-preview0","trusted-modules-only"],"how_to_check":"- Check the Wasmtime version in the host application's lockfile or `wasmtime --version`, and compare it to the fixed releases.\n- Confirm whether the application runs untrusted WebAssembly guest modules that use WASI preview 0 (poll_oneoff).","fix":"- Upgrade Wasmtime to `36.0.17` on the 36 line, `48.0.4` on the 48 line, or `49.0.2` on the 49 line.","status":"open","published_at":"2026-10-22T19:17:44+00:00","first_seen_at":"2026-10-23T21:57:31+00:00","triaged_at":"2026-10-25T04:28:56+00:00","updated_at":"2026-10-25T04:28:56+00:00","category":"runtime","confidence":0.7,"triage":{"at":"2026-10-25T04:28:56Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Wasmtime to `36.0.17` on the 36 line, `48.0.4` on the 48 line, or `49.0.2` on the 49 line.","reach":"unknown","title":"Wasmtime: WASI poll_oneoff lets guest modules stall the host","impact":"low","summary":"Wasmtime's WASI preview 0 poll_oneoff adapter does linear host work per subscription without charging fuel. A malicious guest module can pass many subscriptions and force long host computation that ignores configured fuel limits.","category":"runtime","nicknames":[],"who_cares":["wasmtime","webassembly","wasi","plugin-systems","self-hosted"],"confidence":0.7,"needs_auth":"unknown","worst_case":"Host process stalls on long computation, causing denial of service","analyst_note":"","how_to_check":"- Check the Wasmtime version in the host application's lockfile or `wasmtime --version`, and compare it to the fixed releases.\n- Confirm whether the application runs untrusted WebAssembly guest modules that use WASI preview 0 (poll_oneoff).","needs_analyst":false,"not_affected_if":["trusted-modules-only","no-wasi-preview0"],"who_is_affected":"Applications that embed Wasmtime with wasmtime-wasi and run guest WebAssembly modules that a party outside the team controls, such as plugin systems or multi-tenant function runners. Hosts that run only trusted modules, or that do not use the WASI preview 0 poll_oneoff path, are less exposed.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000631,"input_tokens":3426,"output_tokens":576,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-115380':13A,16A '-2026':12A,15A '0':31B,85C '36.0.17':64C '37.0.0':65C '48.0.4':67C '49.0.0':69C '49.0.2':71C 'adapt':34B,88C 'charg':42B 'check':100C 'comput':56B,115C 'configur':59B,118C 'consum':98C 'contain':72C 'cve':11A,14A 'denial':74C 'forc':53B,110C 'fuel':43B,60B,101C,119C 'guest':6A,46B,103C 'host':10A,23B,37B,55B,93C,114C 'ignor':58B,117C 'let':5A 'limit':61B,120C 'linear':36B 'long':54B,112C 'long-run':111C 'malici':45B,102C 'mani':50B,107C 'modul':7A,47B,104C 'n':92C 'o':91C 'oneoff':4A,33B,87C 'pass':49B,106C 'per':39B,95C 'perform':90C 'plugin':18B 'plugin-system':17B 'poll':3A,32B,86C 'preview':30B,84C 'run':113C 'runtim':20B 'self':22B 'self-host':21B 'servic':76C 'stall':8A 'subscript':40B,51B,96C,108C 'system':19B 'vulner':77C 'wasi':2A,24B,29B,82C,83C 'wasmtim':1A,25B,27B,62C,81C 'wasmtime-wasi':80C 'webassembl':26B 'without':41B,97C 'work':38B,94C","nicknames":[],"mitigations":[],"who_affected":"Applications that embed Wasmtime with wasmtime-wasi and run guest WebAssembly modules that a party outside the team controls, such as plugin systems or multi-tenant function runners. Hosts that run only trusted modules, or that do not use the WASI preview 0 poll_oneoff path, are less exposed.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-22T19:17:44+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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-2026-115380","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-115380","severity":null,"published_at":"2026-10-22T19:17:44+00:00","modified_at":"2026-10-22T19:17:45+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-2026-115380","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-115380","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"}