{"id":"CVE-2026-40669","kind":"vulnerability","aliases":["CVE-2026-40669"],"related":[],"title":"AMD SEV firmware: off-by-one lets hypervisor attacker corrupt guest memory integrity","description":"An off-by-one error in AMD Secure Encrypted Virtualization (SEV) firmware could allow an attacker with hypervisor access to corrupt the Reverse Map Table (RMP) table, potentially resulting in loss of guest memory integrity.","summary":"An off-by-one error in AMD Secure Encrypted Virtualization firmware lets an attacker who already has hypervisor access corrupt the Reverse Map Table. The result is loss of guest memory integrity for virtual machines running on affected AMD hardware.","severity":"medium","cvss":4.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["amd","confidential-computing","hypervisor","infrastructure","sev"],"not_affected_if":["no-sev-enabled","non-amd-hardware"],"how_to_check":null,"fix":null,"status":"open","published_at":"2026-11-10T22:18:32+00:00","first_seen_at":"2026-11-10T22:27:30+00:00","triaged_at":"2026-11-10T22:31:02+00:00","updated_at":"2026-11-10T22:31:02+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-11-10T22:31:02Z","model":"claude-haiku-5-5","output":{"fix":"unknown","reach":"local","title":"AMD SEV firmware: off-by-one lets hypervisor attacker corrupt guest memory integrity","impact":"medium","summary":"An off-by-one error in AMD Secure Encrypted Virtualization firmware lets an attacker who already has hypervisor access corrupt the Reverse Map Table. The result is loss of guest memory integrity for virtual machines running on affected AMD hardware.","audience":"businesses","category":"infrastructure","nicknames":[],"who_cares":["amd","sev","confidential-computing","hypervisor"],"confidence":0.6,"fix_status":"unknown","needs_auth":"yes","worst_case":"Guest VM memory integrity lost via corrupted RMP table","analyst_note":"Find AMD's security bulletin for CVE-2026-40669 to get affected firmware versions and fixed versions; NVD alone does not state them.","how_to_check":"unknown","plain_action":"","product_name":"","needs_analyst":true,"not_affected_if":["no-sev-enabled","non-amd-hardware"],"who_is_affected":"Relevant to operators running confidential virtual machines on AMD EPYC hosts with SEV enabled. The attacker must already have hypervisor access, so hosts without SEV, or without untrusted hypervisor-level access, are unlikely to be exposed. The sources do not list affected firmware versions.","user_interaction":"no","product_ecosystem":"","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000714,"input_tokens":4547,"output_tokens":518,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-2026':16A,19A '-40669':17A,20A 'access':47B,88C 'affect':66B 'allow':83C 'alreadi':44B 'amd':1A,21B,35B,67B,76C 'attack':10A,42B,85C 'comput':24B 'confidenti':23B 'confidential-comput':22B 'corrupt':11A,48B,90C 'could':82C 'cve':15A,18A 'encrypt':37B,78C 'error':33B,74C 'firmwar':3A,39B,81C 'guest':12A,58B,102C 'hardwar':68B 'hypervisor':9A,25B,46B,87C 'infrastructur':26B 'integr':14A,60B,104C 'let':8A,40B 'loss':56B,100C 'machin':63B 'map':51B,93C 'memori':13A,59B,103C 'off-by-on':4A,29B,70C 'one':7A,32B,73C 'potenti':97C 'result':54B,98C 'revers':50B,92C 'rmp':95C 'run':64B 'secur':36B,77C 'sev':2A,27B,80C 'tabl':52B,94C,96C 'virtual':38B,62B,79C","nicknames":[],"mitigations":[],"who_affected":"Relevant to operators running confidential virtual machines on AMD EPYC hosts with SEV enabled. The attacker must already have hypervisor access, so hosts without SEV, or without untrusted hypervisor-level access, are unlikely to be exposed. The sources do not list affected firmware versions.","tier":"C","verified":{},"analyst_revisit_at":null,"fix_status":"none","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["amd","confidentialcomputing","hypervisor","infrastructure","medium","sev"],"campaign_type":null,"search_a":"'-2026':16A,19A '-40669':17A,20A 'amd':1A 'attack':10A 'corrupt':11A 'cve':15A,18A 'firmwar':3A 'guest':12A 'hypervisor':9A 'integr':14A 'let':8A 'memori':13A 'off-by-on':4A 'one':7A 'sev':2A","search_b":"'access':47B 'affect':66B 'alreadi':44B 'amd':21B,35B,67B 'attack':42B 'comput':24B 'confidenti':23B 'confidential-comput':22B 'corrupt':48B 'encrypt':37B 'error':33B 'firmwar':39B 'guest':58B 'hardwar':68B 'hypervisor':25B,46B 'infrastructur':26B 'integr':60B 'let':40B 'loss':56B 'machin':63B 'map':51B 'memori':59B 'off-by-on':29B 'one':32B 'result':54B 'revers':50B 'run':64B 'secur':36B 'sev':27B 'tabl':52B 'virtual':38B,62B","search_c":"'access':88C 'allow':83C 'amd':76C 'attack':85C 'corrupt':90C 'could':82C 'encrypt':78C 'error':74C 'firmwar':81C 'guest':102C 'hypervisor':87C 'integr':104C 'loss':100C 'map':93C 'memori':103C 'off-by-on':70C 'one':73C 'potenti':97C 'result':98C 'revers':92C 'rmp':95C 'secur':77C 'sev':80C 'tabl':94C,96C 'virtual':79C","cause_entry":null,"cause_path":null,"disclosures_checked_at":null,"first_public_at":"2026-11-10T22:18:32+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/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":"psirt@amd.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-40669","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40669","severity":null,"published_at":"2026-11-10T22:18:32+00:00","modified_at":"2026-11-10T22:18:32+00:00","first_seen_at":"2026-11-10T22:27:30+00:00","fetched_at":"2026-11-10T22:27:30+00:00","note":null}],"documents":[],"disclosures":[],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}