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CVE-2026-64530

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle tcf_classify() can return TC_ACT_CONSUMED while the skb is held by the defragmentation engine (e.g. act_ct on out-of-order fragments). When that happens the skb is no longer owned by the caller and must not be touched again. tcf_qevent_handle() did not handle TC_ACT_CONSUMED: it fell through the switch and returned the skb to the caller as if classification had passed. The only qdisc that wires up qevents today is RED, via three call sites (qe_mark on RED_PROB_MARK/HARD_MARK, qe_early_drop on congestion_drop) red_enqueue() was continuing to operate on an skb it no longer owns in this case -- enqueueing it, dropping it, or updating statistics. Resulting in a UAF. tc qdisc add dev eth0 root handle 1: red ... qevent early_drop block 10 tc filter add block 10 ... action ct (with ct defrag enabled and traffic that produces out-of-order fragments, e.g. a fragmented UDP stream) Handle TC_ACT_CONSUMED in tcf_qevent_handle() the same way the ingress and egress fast paths do: treat it as stolen and return NULL without touching the skb. Unlike the TC_ACT_STOLEN case, the skb must not be dropped/freed here, as it is no longer owned by us.

Severity
CRITICAL
CVSS score
9.8 (v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-07-26 07:16:41.680000
Last modified
2026-10-19 21:17:42.333000
View original CVE JSON 
{
  "id": "CVE-2026-64530",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-07-26T07:16:41.680",
  "lastModified": "2026-10-19T21:17:42.333",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle\n\ntcf_classify() can return TC_ACT_CONSUMED while the skb is held by the\ndefragmentation engine (e.g. act_ct on out-of-order fragments). When\nthat happens the skb is no longer owned by the caller and must not be\ntouched again.\n\ntcf_qevent_handle() did not handle TC_ACT_CONSUMED: it fell through the\nswitch and returned the skb to the caller as if classification had\npassed. The only qdisc that wires up qevents today is RED, via three call sites\n(qe_mark on RED_PROB_MARK/HARD_MARK, qe_early_drop on congestion_drop)\nred_enqueue() was continuing to operate on an skb it no longer owns  in this\ncase -- enqueueing it, dropping it, or updating statistics. Resulting in a UAF.\n\n  tc qdisc add dev eth0 root handle 1: red ... qevent early_drop block 10\n  tc filter add block 10 ... action ct\n\n  (with ct defrag enabled and traffic that produces out-of-order\n  fragments, e.g. a fragmented UDP stream)\n\nHandle TC_ACT_CONSUMED in tcf_qevent_handle() the same way the ingress\nand egress fast paths do: treat it as stolen and return NULL without\ntouching the skb. Unlike the TC_ACT_STOLEN case, the skb must not be\ndropped/freed here, as it is no longer owned by us."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "172ba7d46c202e679f3ccb10264c67416aaeb1c4",
              "lessThan": "5ed3d6f85991656667059d3fa5a1d683ac58c447",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "0b5b831122fc3789fff75be433ba3e4dd7b779d4",
              "lessThan": "f42e8134a3a1074b834a574d404352f867ba994a",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "73f7da5fd124f2cda9161e2e46114915e6e82e97",
              "lessThan": "447d493034a9cf7bf13a2abac86d0573d907ec2f",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6",
              "lessThan": "e1270e69dcf2c3512c453484178f2e9dc0db3f05",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6",
              "lessThan": "2140c2f3f2e7b066e1ae616ede8856cafd8015e9",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6",
              "lessThan": "e28aedab9488343924d227b5a896faed67ce84d5",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "3f14b377d01d8357eba032b4cabc8c1149b458b6",
              "lessThan": "a8a02897f2b479127db261de05cbf0c28b98d159",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "f5346df0591d10bc948761ca854b1fae6d2ef441",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "5.15.148",
              "lessThan": "5.15.212",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "6.1.75",
              "lessThan": "6.1.178",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "6.6.14",
              "lessThan": "6.6.145",
              "versionType": "semver",
              "status": "affected"
            },
            {
              "version": "6.7.2",
              "lessThan": "6.8",
              "versionType": "semver",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "6.8",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "6.8",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.212",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.178",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.145",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.97",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.40",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1.5",
              "lessThanOrEqual": "7.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T15:41:44.353854Z",
          "id": "CVE-2026-64530",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2140c2f3f2e7b066e1ae616ede8856cafd8015e9",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/447d493034a9cf7bf13a2abac86d0573d907ec2f",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/5ed3d6f85991656667059d3fa5a1d683ac58c447",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/a8a02897f2b479127db261de05cbf0c28b98d159",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "url": "https://git.kernel.org/stable/c/e1270e69dcf2c3512c453484178f2e9dc0db3f05",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  ]
}