FKIE_CVE-2026-98622

Vulnerability from fkie_nvd - Published: 2026-10-18 16:17 - Updated: 2026-10-19 10:19
Severity
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.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/act_ct.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e8fcf3f08834e939b797311742ee72b1e2a08096",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "af475f599270e59313552e6c6f3af8507da672b8",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "424ba52c0058deeb940d02cba52eb0aeb288db33",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "d805560ad69cb266d669341ca01e26bffb0d2c67",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "00734f3684fcec42c319bedfe68a5d357c720b53",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "650787233c2fd6e515a7c5f371019a9fa080ccd2",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            },
            {
              "lessThan": "47abe7a5c4eb53269aca3506446f851572a059a3",
              "status": "affected",
              "version": "64ff70b80fd403110b67dd9f7184a604fdb0da43",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sched/act_ct.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.7"
            },
            {
              "lessThan": "5.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.112",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.55",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure\n\nflow_offload_alloc() returns NULL when the conntrack entry is dying\n(e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation\nfails; both are expected under load and neither is a kernel bug. This\npath runs from softirq on every committed packet, so with\npanic_on_warn=1 an unprivileged user can panic the box just by racing\na conntrack flush against a `tc ... action ct commit` classifier.\n\nReproduced with a custom repro under QEMU: a small, fixed set of UDP\nflows through `tc filter ... action ct commit` on lo, raced against\nthreads flooding bare ctnetlink CT_DELETE (flush) requests. Hits\nWARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined\ninto tcf_ct_act() in this build) within ~15s on the unpatched kernel;\nsame setup is clean on the patched kernel. The fix itself is\nbehavior-preserving: both branches already did `goto err_alloc`\nbefore and after, only the WARN is removed."
    }
  ],
  "id": "CVE-2026-98622",
  "lastModified": "2026-10-19T10:19:26.330",
  "metrics": {},
  "published": "2026-10-18T16:17:15.117",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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