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net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.271, 5.15.222, 6.1.189, 6.12.112, 6.18.55, 6.6.158, 7.2.9
CVEs
CVE-2026-98622
Confirmed fixed CVEs
Not specified
Updated in this feed
3 Nov 2026, 02:59 UTC · Revision 1

Source evidence

net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure

core-osv · Original source

Published 18 Oct 2026, 15:19 UTC

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.

osv:CVE-2026-98622

Kernel

Fixed versions: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, 6.18.55, 7.2.9

Complete source record
{
  "id": "4c929f6f237be564adfaed9365bbe7b2baca3cd021f044633b89c4a822c8b3b2",
  "url": "https://osv.dev/vulnerability/CVE-2026-98622",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.",
    "evidence": "osv:CVE-2026-98622",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.271",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.222",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.189",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.158",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.112",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.55",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98622",
      "aliases": [
        "CVE-2026-98622"
      ],
      "affected": [
        {
          "ranges": [
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              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                },
                {
                  "fixed": "af475f599270e59313552e6c6f3af8507da672b8"
                },
                {
                  "fixed": "424ba52c0058deeb940d02cba52eb0aeb288db33"
                },
                {
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                {
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                {
                  "fixed": "00734f3684fcec42c319bedfe68a5d357c720b53"
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                {
                  "fixed": "47abe7a5c4eb53269aca3506446f851572a059a3"
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          ],
          "database_specific": {
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          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.7.0"
                },
                {
                  "fixed": "5.10.271"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.222"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.1.189"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
                },
                {
                  "fixed": "6.6.158"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.7.0"
                },
                {
                  "fixed": "6.12.112"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.18.55"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
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                {
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98622.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:25.298174897Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53",
        "https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33",
        "https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3",
        "https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2",
        "https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8",
        "https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a",
        "https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67",
        "https://git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98622.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98622",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98622.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98622",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492082,
  "published_at": "2026-10-18T15:19:42.514+00:00"
}