{
  "cveId": "CVE-2026-90099",
  "url": "https://patchblox.com/security/cve/CVE-2026-90099",
  "summary": "CVE-2026-90099 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-90099, 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:  net/sched: account classifier filter allocations...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  net/sched: account classifier filter allocations to memcg  Allocations in the tc classifier *_change() paths (filter objects, per-CPU counters, and per-filter aux data) use plain GFP_KERNEL without __GFP_ACCOUNT, allowing unprivileged users to pin kernel memory outside memcg charging. The shared tcf_exts_init_ex() action array allocation in cls_api.c was also uncharged; this patch closes it along with the per-classifier filter-object/percpu/aux allocations that remain unaccounted.  Add GFP_KERNEL_ACCOUNT to: - the shared tcf_exts_init_ex() action array (cls_api.c), common to every   filter of every classifier (32 pointers, 256 bytes); - the filter-object, per-CPU-counter, and per-filter aux allocations in   cls_basic, cls_bpf, cls_cgroup, cls_flow, cls_flower, cls_fw,   cls_matchall, cls_route and cls_u32; - the u32_init_knode() replace-path knode allocation (cls_u32.c), which   allocates the same struct tc_u_knode \u002B sel.keys on every replace of an   existing knode and was missed by the create-path-only conversion.  Also fix the cls_basic error path: basic_change() inserts fnew into the IDR before allocating the per-CPU counter. If alloc_percpu() fails the errout path kfree\u0027d fnew without idr_remove, leaving a dangling pointer in the IDR. With GFP_KERNEL_ACCOUNT the percpu alloc becomes failable on demand (memcg at memory.max), making the dead path attacker-reachable and burning the handle permanently. Add the idr_remove on the percpu failure path, matching the basic_set_parms failure-path pattern.  Note: vega@nebusec.ai provided a poc for basic_cls, but it was easy to extend to the other classifiers.  Conditions to recreate the bug: - CONFIG_NET_SCHED, CONFIG_NET_CLS_* (the classifier being used),   CONFIG_NET_CLS_ACT, CONFIG_MEMCG, CONFIG_USER_NS, CONFIG_NET_NS. - Unprivileged user in a fresh user\u002Bnetwork namespace (unshare -Urn),   or root with CAP_NET_ADMIN. - Create a large number of tc filters (e.g. tc filter add dev lo   ingress ... \u003Cclassifier\u003E ...) while watching a memcg-limited cgroup:   system slab grows far faster than memory.current, pinning kernel   memory outside memcg charging.",
  "published": "2026-09-17T17:17:01Z",
  "severity": "",
  "epss": 0.00215,
  "epssPercentile": 0.11904,
  "priority": "Routine",
  "priorityTier": 4,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "6.12.115-2",
      "fix": "DEBIAN-CVE-2026-90099",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-90099",
      "released": "2026-09-23T19:19:02Z"
    },
    {
      "platform": "linux",
      "product": "linux",
      "release": "Debian 14",
      "fixedVersion": "7.2.6-1",
      "fix": "DEBIAN-CVE-2026-90099",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-90099",
      "released": "2026-09-23T19:19:02Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}