{"id":"CVE-2026-98857","kind":"vulnerability","aliases":["CVE-2026-98857"],"related":[],"title":"Linux kernel IPVS: unbounded LBLC cache growth lets traffic exhaust memory","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: bound LBLCR and LBLC cache growth\n\nip_vs_lblcr_new() and ip_vs_lblc_new() create cache entries for\nevery previously unseen destination address. The table max_size only\ntells the periodic collector to reclaim entries after the cache has\nalready exceeded the limit. It does not reclaim entries that the\nattacker continues to use.\n\nReject new cache entries once either table reaches max_size * 3 / 2.\nThe extra headroom lets the periodic collector catch up while the\nexisting scheduler fallback continues to use the selected destination\nwhen cache creation fails. New traffic therefore stays serviceable\nwithout growing the tables further.","summary":"The Linux kernel's IPVS load balancer creates a cache entry for every new destination address in its LBLC and LBLCR schedulers, and the size limit only triggers cleanup after it is already exceeded. An attacker sending traffic from many addresses can grow these tables without bound, consuming kernel memory.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["ipvs","kernel","linux","load-balancer","runtime","self-hosted"],"not_affected_if":["no-ipvs","other-scheduler"],"how_to_check":"- unknown","fix":"- Install a kernel release that includes the upstream commit 'ipvs: bound LBLCR and LBLC cache growth'; the sources do not name the fixed version numbers.","status":"open","published_at":"2026-10-18T16:17:40+00:00","first_seen_at":"2026-10-23T21:57:17+00:00","triaged_at":"2026-10-25T05:12:56+00:00","updated_at":"2026-10-25T05:12:56+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-25T05:12:56Z","model":"claude-haiku-5-5","output":{"fix":"- Install a kernel release that includes the upstream commit 'ipvs: bound LBLCR and LBLC cache growth'; the sources do not name the fixed version numbers.","reach":"network","title":"Linux kernel IPVS: unbounded LBLC cache growth lets traffic exhaust memory","impact":"medium","summary":"The Linux kernel's IPVS load balancer creates a cache entry for every new destination address in its LBLC and LBLCR schedulers, and the size limit only triggers cleanup after it is already exceeded. An attacker sending traffic from many addresses can grow these tables without bound, consuming kernel memory.","category":"runtime","nicknames":[],"who_cares":["linux","kernel","ipvs","load-balancer","self-hosted"],"confidence":0.5,"needs_auth":"no","worst_case":"Remote traffic exhausts kernel memory, causing denial of service on the load balancer","analyst_note":"Find the fixed kernel versions and the upstream commit in the kernel stable mailing list or NVD entry to fill in fix and how_to_check.","how_to_check":"- unknown","needs_analyst":true,"not_affected_if":["no-ipvs","other-scheduler"],"who_is_affected":"Only systems running IP Virtual Server (ipvs) with the LBLC or LBLCR scheduler are exposed, typically Linux load balancers in front of services. Hosts that do not use IPVS, or use other schedulers, can skip it. The sources do not say which kernel versions are affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000628,"input_tokens":3457,"output_tokens":565,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':13A,16A '-98857':14A,17A '2':155C '3':154C 'address':43B,68B,112C 'alreadi':60B,129C 'attack':63B,140C 'balanc':23B,34B 'bound':74B,89C 'cach':6A,37B,93C,105C,127C,146C,177C 'catch':163C 'cleanup':56B 'collector':121C,162C 'consum':75B 'continu':141C,170C 'creat':35B,104C 'creation':178C 'cve':12A,15A 'destin':42B,111C,175C 'either':149C 'entri':38B,106C,124C,137C,147C 'everi':40B,108C 'exceed':61B,130C 'exhaust':10A 'exist':167C 'extra':157C 'fail':179C 'fallback':169C 'follow':83C 'grow':70B,186C 'growth':7A,94C 'headroom':158C 'host':27B 'ip':95C,100C 'ipv':3A,18B,32B,88C 'kernel':2A,19B,30B,76B,81C 'lblc':5A,46B,92C,102C 'lblcr':48B,90C,97C 'let':8A,159C 'limit':53B,132C 'linux':1A,20B,29B,80C 'load':22B,33B 'load-balanc':21B 'mani':67B 'max':115C,152C 'memori':11A,77B 'new':41B,98C,103C,145C,180C 'period':120C,161C 'previous':109C 'reach':151C 'reclaim':123C,136C 'reject':144C 'resolv':87C 'runtim':24B 'schedul':49B,168C 'select':174C 'self':26B 'self-host':25B 'send':64B 'servic':184C 'size':52B,116C,153C 'stay':183C 'tabl':72B,114C,150C,188C 'tell':118C 'therefor':182C 'traffic':9A,65B,181C 'trigger':55B 'unbound':4A 'unseen':110C 'use':143C,172C 'vs':96C,101C 'vulner':84C 'without':73B,185C","nicknames":[],"mitigations":[],"who_affected":"Only systems running IP Virtual Server (ipvs) with the LBLC or LBLCR scheduler are exposed, typically Linux load balancers in front of services. Hosts that do not use IPVS, or use other schedulers, can skip it. The sources do not say which kernel versions are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-18T16:17:40+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98857","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98857","severity":null,"published_at":"2026-10-18T16:17:40+00:00","modified_at":"2026-10-21T13:21:50+00:00","first_seen_at":"2026-10-23T21:57:17+00:00","fetched_at":"2026-10-23T22:28:56+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"}