{"id":"CVE-2026-93866","kind":"vulnerability","aliases":["CVE-2026-93866"],"related":[],"title":"WatchGuard Fireware OS: WebSocket integer overflow lets unauthenticated attackers write heap memory","description":"An integer overflow vulnerability in the WebSocket connection handling used by WatchGuard Fireware OS's Access Portal allows a remote, unauthenticated attacker to write beyond the bounds of a heap buffer by sending a specially crafted request while the Access Portal feature is enabled.","summary":"An integer overflow in the WebSocket handling of WatchGuard Fireware OS's Access Portal lets a remote attacker write past the end of a heap buffer. The sources do not say whether this leads to code execution, but the memory corruption is reachable without credentials.","severity":"critical","cvss":9.2,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["access-portal","firewall","fireware-os","infrastructure","watchguard"],"not_affected_if":["access-portal-disabled"],"how_to_check":"- Log in to the Fireware web UI or run the device's status command and confirm the Fireware OS version.\n- Check whether the Access Portal feature is enabled in the device configuration.","fix":"- Upgrade Fireware OS to a patched release listed in the WatchGuard advisory (version unknown from the sources).\n- Disable the Access Portal feature until patched if it is not needed.","status":"open","published_at":"2026-10-27T16:17:33+00:00","first_seen_at":"2026-10-27T16:33:07+00:00","triaged_at":"2026-10-27T16:33:55+00:00","updated_at":"2026-10-27T16:33:55+00:00","category":"infrastructure","confidence":0.6,"triage":{"at":"2026-10-27T16:33:55Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade Fireware OS to a patched release listed in the WatchGuard advisory (version unknown from the sources).\n- Disable the Access Portal feature until patched if it is not needed.","reach":"internet","title":"WatchGuard Fireware OS: WebSocket integer overflow lets unauthenticated attackers write heap memory","impact":"high","summary":"An integer overflow in the WebSocket handling of WatchGuard Fireware OS's Access Portal lets a remote attacker write past the end of a heap buffer. The sources do not say whether this leads to code execution, but the memory corruption is reachable without credentials.","category":"infrastructure","nicknames":[],"who_cares":["watchguard","fireware-os","firewall","access-portal"],"confidence":0.6,"needs_auth":"no","worst_case":"Remote unauthenticated attacker corrupts heap memory on the firewall","analyst_note":"Find the WatchGuard advisory for CVE-2026-93866 to get affected and fixed Fireware OS versions and confirm whether the flaw enables code execution.","how_to_check":"- Log in to the Fireware web UI or run the device's status command and confirm the Fireware OS version.\n- Check whether the Access Portal feature is enabled in the device configuration.","needs_analyst":true,"not_affected_if":["access-portal-disabled"],"who_is_affected":"Organizations running WatchGuard Fireware OS firewalls with the Access Portal feature enabled are exposed, since the flaw is triggered by a crafted WebSocket request to that feature. Devices with Access Portal disabled, or teams running other vendors' firewalls, can skip it. The sources do not list affected Fireware versions.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000645,"input_tokens":3317,"output_tokens":627,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-2026':14A,17A '-93866':15A,18A 'access':20B,40B,88C,112C 'access-port':19B 'allow':90C 'attack':9A,45B,94C 'beyond':97C 'bound':99C 'buffer':53B,103C 'code':63B 'connect':80C 'corrupt':68B 'craft':108C 'credenti':72B 'cve':13A,16A 'enabl':116C 'end':49B 'execut':64B 'featur':114C 'firewal':22B 'firewar':2A,24B,37B,85C 'fireware-o':23B 'handl':34B,81C 'heap':11A,52B,102C 'infrastructur':26B 'integ':5A,29B,74C 'lead':61B 'let':7A,42B 'memori':12A,67B 'os':3A,25B,38B,86C 'overflow':6A,30B,75C 'past':47B 'portal':21B,41B,89C,113C 'reachabl':70B 'remot':44B,92C 'request':109C 'say':58B 'send':105C 'sourc':55B 'special':107C 'unauthent':8A,93C 'use':82C 'vulner':76C 'watchguard':1A,27B,36B,84C 'websocket':4A,33B,79C 'whether':59B 'without':71B 'write':10A,46B,96C","nicknames":[],"mitigations":[],"who_affected":"Organizations running WatchGuard Fireware OS firewalls with the Access Portal feature enabled are exposed, since the flaw is triggered by a crafted WebSocket request to that feature. Devices with Access Portal disabled, or teams running other vendors' firewalls, can skip it. The sources do not list affected Fireware versions.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-27T16:17:33+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/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":"5d1c2695-1a31-4499-88ae-e847036fd7e3","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-93866","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93866","severity":null,"published_at":"2026-10-27T16:17:33+00:00","modified_at":"2026-10-27T16:17:33+00:00","first_seen_at":"2026-10-27T16:33:07+00:00","fetched_at":"2026-10-27T16:33:07+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"}