{"id":"CVE-2020-37287","kind":"vulnerability","aliases":["CVE-2020-37287"],"related":[],"title":"Vyper: call stack corruption garbles arrays and structs passed to functions","description":"Vyper before 0.2.6 contains a call stack corruption vulnerability that causes incorrect function outputs when complex types with non-base members are passed as arguments. Contracts passing multi-dimensional arrays or structs to internal or external functions receive corrupted values because the compiler assumed each subtype size is 32.","summary":"Vyper versions before 0.2.6 corrupt the call stack when multi-dimensional arrays or structs are passed as arguments, so functions receive wrong values. An attacker who can influence those inputs can make a contract act on incorrect data.","severity":"high","cvss":8.2,"epss":0.00251,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ethereum","package","smart-contracts","vyper"],"not_affected_if":["base-type-arguments-only","vyper-0.2.6-or-later"],"how_to_check":"- Run `vyper --version` and check whether it is below `0.2.6`\n- Search contract source and build config for pinned Vyper versions below `0.2.6`","fix":"- Upgrade Vyper to `0.2.6` or later and recompile contracts\n- Re-test contract functions that take arrays or structs as arguments","status":"open","published_at":"2026-10-21T01:17:18+00:00","first_seen_at":"2026-10-23T21:57:27+00:00","triaged_at":"2026-10-25T03:03:53+00:00","updated_at":"2026-10-25T03:03:53+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-25T03:03:53Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Vyper to `0.2.6` or later and recompile contracts\n- Re-test contract functions that take arrays or structs as arguments","reach":"unknown","title":"Vyper: call stack corruption garbles arrays and structs passed to functions","impact":"medium","summary":"Vyper versions before 0.2.6 corrupt the call stack when multi-dimensional arrays or structs are passed as arguments, so functions receive wrong values. An attacker who can influence those inputs can make a contract act on incorrect data.","category":"package","nicknames":[],"who_cares":["vyper","smart-contracts","ethereum"],"confidence":0.7,"needs_auth":"unknown","worst_case":"contract functions receive corrupted inputs and return wrong outputs","analyst_note":"","how_to_check":"- Run `vyper --version` and check whether it is below `0.2.6`\n- Search contract source and build config for pinned Vyper versions below `0.2.6`","needs_analyst":false,"not_affected_if":["vyper-0.2.6-or-later","base-type-arguments-only"],"who_is_affected":"Teams that compile smart contracts with Vyper before 0.2.6 are exposed, especially contracts that pass multi-dimensional arrays or structs to internal or external functions. Projects using only base-type arguments or a newer compiler can skip it.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000591,"input_tokens":3362,"output_tokens":510,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-2020':13A,16A '-37287':14A,17A '0.2.6':27B,65C '32':113C 'act':59B 'argument':42B,88C 'array':6A,36B,94C 'assum':108C 'attack':49B 'base':83C 'call':2A,30B,68C 'caus':73C 'compil':107C 'complex':78C 'contain':66C 'contract':22B,58B,89C 'corrupt':4A,28B,70C,103C 'cve':12A,15A 'data':62B 'dimension':35B,93C 'ethereum':18B 'extern':100C 'function':11A,44B,75C,101C 'garbl':5A 'incorrect':61B,74C 'influenc':52B 'input':54B 'intern':98C 'make':56B 'member':84C 'multi':34B,92C 'multi-dimension':33B,91C 'non':82C 'non-bas':81C 'output':76C 'packag':19B 'pass':9A,40B,86C,90C 'receiv':45B,102C 'size':111C 'smart':21B 'smart-contract':20B 'stack':3A,31B,69C 'struct':8A,38B,96C 'subtyp':110C 'type':79C 'valu':47B,104C 'version':25B 'vulner':71C 'vyper':1A,23B,24B,63C 'wrong':46B","nicknames":[],"mitigations":[],"who_affected":"Teams that compile smart contracts with Vyper before 0.2.6 are exposed, especially contracts that pass multi-dimensional arrays or structs to internal or external functions. Projects using only base-type arguments or a newer compiler can skip it.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-21T01:17:18+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/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-2020-37287","url":"https://nvd.nist.gov/vuln/detail/CVE-2020-37287","severity":null,"published_at":"2026-10-21T01:17:18+00:00","modified_at":"2026-10-22T17:00:33+00:00","first_seen_at":"2026-10-23T21:57:27+00:00","fetched_at":"2026-10-23T22:29:01+00:00","note":null},{"source":"epss","external_id":"CVE-2020-37287","url":"https://api.first.org/data/v1/epss?cve=CVE-2020-37287","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-24T13:15:55+00:00","fetched_at":"2026-10-24T13:15:55+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"}