{"id":"CVE-2026-63418","kind":"vulnerability","aliases":["CVE-2026-63418"],"related":[],"title":"Monitoring Plugins: check_icmp heap overflow can escalate local privileges","description":"Monitoring Plugins is a suite of plugins for monitoring applications. From 3.0.0-rc1 until 3.0.1, check_icmp stores the number of hosts supplied through -H or --Host on the command line, or through --extra-opts files containing Host= entries, in an unsigned short. More than 65,535 hosts wrap the counter, causing process_arguments() to allocate an undersized hosts array and then write subsequent entries out of bounds before main() calls setuid(getuid()). On installations where check_icmp is setuid root, a local low-privileged attacker can corrupt heap memory while the process still has root privileges; reliable privilege escalation has not been demonstrated. Installations that use cap_net_raw file capabilities instead of setuid are not exposed to the privilege-escalation consequence. This issue is fixed in version 3.0.1.","summary":"Monitoring Plugins' check_icmp stores its host count in an unsigned short, so more than 65,535 hosts wrap the counter and cause out-of-bounds writes. On setuid-root installs a local low-privileged user can corrupt heap memory while still running as root, though reliable escalation has not been demonstrated.","severity":"high","cvss":7.0,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["linux","monitoring-plugins","nagios","package","self-hosted"],"not_affected_if":["cap-net-raw-instead-of-setuid","version-3.0.1-or-later","version-below-3.0.0-rc1"],"how_to_check":"- Run `check_icmp --version` or look at the installed Monitoring Plugins version.\n- Check whether the binary is setuid root with `ls -l $(which check_icmp)`.\n- Check whether file capabilities are used instead with `getcap $(which check_icmp)`.","fix":"- Monitoring Plugins `3.0.1`","status":"open","published_at":"2026-11-03T18:18:03+00:00","first_seen_at":"2026-11-03T18:22:10+00:00","triaged_at":"2026-11-03T18:22:33+00:00","updated_at":"2026-11-03T18:22:33+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-03T18:22:33Z","model":"claude-haiku-5-5","output":{"fix":"- Monitoring Plugins `3.0.1`","reach":"local","title":"Monitoring Plugins: check_icmp heap overflow can escalate local privileges","impact":"high","summary":"Monitoring Plugins' check_icmp stores its host count in an unsigned short, so more than 65,535 hosts wrap the counter and cause out-of-bounds writes. On setuid-root installs a local low-privileged user can corrupt heap memory while still running as root, though reliable escalation has not been demonstrated.","audience":"businesses","category":"package","nicknames":[],"who_cares":["monitoring-plugins","nagios","linux","self-hosted"],"confidence":0.6,"fix_status":"available","needs_auth":"yes","worst_case":"local user corrupts heap memory of a root-privileged process","analyst_note":"","how_to_check":"- Run `check_icmp --version` or look at the installed Monitoring Plugins version.\n- Check whether the binary is setuid root with `ls -l $(which check_icmp)`.\n- Check whether file capabilities are used instead with `getcap $(which check_icmp)`.","plain_action":"","needs_analyst":false,"not_affected_if":["cap-net-raw-instead-of-setuid","version-below-3.0.0-rc1","version-3.0.1-or-later"],"who_is_affected":"Only installations from 3.0.0-rc1 through 3.0.1 where check_icmp is setuid root are exposed to the privilege-escalation consequence. Installations using cap_net_raw file capabilities instead of setuid are not exposed to that consequence. Teams that run check_icmp only with the default non-setuid setup can skip the escalation concern.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000744,"input_tokens":4335,"output_tokens":622,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-63418':13A,16A '3.0.0':92C '3.0.1':95C,213C '535':42B,128C '65':41B,127C 'alloc':137C 'applic':90C 'argument':135C 'array':141C 'attack':168C 'bound':52B,149C 'call':152C 'cap':190C 'capabl':194C 'caus':48B,133C 'check':3A,28B,96C,158C 'command':110C 'consequ':206C 'contain':118C 'corrupt':66B,170C 'count':33B 'counter':46B,132C 'cve':11A,14A 'demonstr':80B,186C 'entri':120C,146C 'escal':8A,76B,182C,205C 'expos':200C 'extra':115C 'extra-opt':114C 'file':117C,193C 'fix':210C 'getuid':154C 'h':105C 'heap':5A,67B,171C 'host':25B,32B,43B,102C,107C,119C,129C,140C 'icmp':4A,29B,97C,159C 'instal':58B,156C,187C 'instead':195C 'issu':208C 'line':111C 'linux':17B 'local':9A,60B,164C 'low':62B,166C 'low-privileg':61B,165C 'main':151C 'memori':68B,172C 'monitor':1A,19B,26B,81C,89C 'monitoring-plugin':18B 'nagio':21B 'net':191C 'number':100C 'opt':116C 'out-of-bound':49B 'overflow':6A 'packag':22B 'plugin':2A,20B,27B,82C,87C 'privileg':10A,63B,167C,179C,181C,204C 'privilege-escal':203C 'process':134C,175C 'raw':192C 'rc1':93C 'reliabl':75B,180C 'root':57B,73B,162C,178C 'run':71B 'self':24B 'self-host':23B 'setuid':56B,153C,161C,197C 'setuid-root':55B 'short':37B,124C 'still':70B,176C 'store':30B,98C 'subsequ':145C 'suit':85C 'suppli':103C 'though':74B 'unders':139C 'unsign':36B,123C 'use':189C 'user':64B 'version':212C 'wrap':44B,130C 'write':53B,144C","nicknames":[],"mitigations":[],"who_affected":"Only installations from 3.0.0-rc1 through 3.0.1 where check_icmp is setuid root are exposed to the privilege-escalation consequence. Installations using cap_net_raw file capabilities instead of setuid are not exposed to that consequence. Teams that run check_icmp only with the default non-setuid setup can skip the escalation concern.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"businesses","plain_action":null,"pkeys":[],"ptokens":[],"labels":["high","linux","monitoringplugins","nagios","package","selfhosted"],"campaign_type":null,"first_public_at":"2026-07-01T12:39:19+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-63418","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-63418","severity":null,"published_at":"2026-11-03T18:18:03+00:00","modified_at":"2026-11-03T18:18:03+00:00","first_seen_at":"2026-11-03T18:22:10+00:00","fetched_at":"2026-11-03T18:22:10+00:00","note":null}],"documents":[{"id":59664,"url":"https://github.com/monitoring-plugins/monitoring-plugins/commit/c35c12e58d326ffbd6cfb3c9097653f9f3fb2f4a","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":59665,"url":"https://github.com/monitoring-plugins/monitoring-plugins/releases/tag/v3.0.1","title":"Release notes: github.com","kind":"release","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Release notes: github.com"},{"id":59666,"url":"https://github.com/monitoring-plugins/monitoring-plugins/security/advisories/GHSA-xvvw-4j77-rp7q","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-07-01T12:39:19+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}