{
  "cveId": "CVE-2026-93197",
  "url": "https://patchblox.com/security/cve/CVE-2026-93197",
  "summary": "CVE-2026-93197 is fixed in linux on 1 platform by DEBIAN-CVE-2026-93197 (version 7.2.6-1), released September 23, 2026. It is not reported as exploited. Patch Radar priority: Routine.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  memcg: move LRU size accounting on reparenting i...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  memcg: move LRU size accounting on reparenting instead of copying it  When a memory cgroup is offlined its LRU folios are reparented to the parent.  lruvec_reparent_lru() splices the child\u0027s lists into the parent\u0027s and credits the parent with the child\u0027s per-zone lru_zone_size[], but never clears the child\u0027s copy, so the size is copied rather than moved.  lru_gen_reparent_memcg() does the same for MGLRU.  The parent is left correct, credited with exactly the folios it took over.  The stale value sits on the child and nothing will correct it: folio-\u003Ememcg_data now resolves to the parent, so every later update_lru_size() for those folios goes there.  Dying cgroups are not freed immediately and mem_cgroup_iter() still walks them, so shrink_lruvec() keeps being called on them. get_scan_count() reads the phantom counter through lruvec_lru_size() and the scan loop then grinds through nr[] in SWAP_CLUSTER_MAX steps against an empty list, for as long as the dead cgroup lives.  Under MGLRU the MGLRU scanner runs instead, but count_shadow_nodes() sums all of NR_LRU_LISTS through lruvec_lru_size() and over-budgets the shadow node limit just the same.  On one 251 GiB host a sweep of every mz-\u003Elru_zone_size[] found 380 counters describing folios on no list at all: 124777314 pages, 476 GiB, 1.89x the machine\u0027s RAM, across 57 cgroups.  All were on memcgs with CSS_DYING set and CSS_ONLINE clear, and parent/child pairs reported byte-identical sizes.  LRU_UNEVICTABLE needs its size moved too.  Its list is deliberately not spliced because lruvec_init() poisons the head - the unevictable LRU is imaginary and folios are never threaded on it - but the size is kept by lruvec_add_folio()/lruvec_del_folio() and those folios account to the parent from here on.  This depends on commit bf4ade7dbd76 (\u0022memcg: keep folio\u0027s objcg same as its node\u0022) and must not be backported ahead of it.  Without that invariant a folio\u0027s objcg can belong to another node, so a folio already spliced onto the parent\u0027s list can still resolve to the child\u0027s lruvec until the objcg\u0027s node is reparented in a later iteration of memcg_reparent_objcgs(); clearing the child\u0027s counter early then lets lruvec_del_folio() underflow it and trip the WARN_ONCE()/VM_BUG_ON() in mem_cgroup_update_lru_size().",
  "published": "2026-09-17T17:18:15Z",
  "severity": "",
  "epss": 0.00198,
  "epssPercentile": 0.09555,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-93197",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-93197",
      "released": "2026-09-23T19:19:02Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T19:38:12Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}