CVE-2026-23270 (GCVE-0-2026-23270)
Vulnerability from cvelistv5
Published
2026-03-18 17:54
Modified
2026-04-18 08:57
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/
References
Impacted products
Vendor Product Version
Linux Linux Version: 172ba7d46c202e679f3ccb10264c67416aaeb1c4
Version: 0b5b831122fc3789fff75be433ba3e4dd7b779d4
Version: 73f7da5fd124f2cda9161e2e46114915e6e82e97
Version: 3f14b377d01d8357eba032b4cabc8c1149b458b6
Version: 3f14b377d01d8357eba032b4cabc8c1149b458b6
Version: 3f14b377d01d8357eba032b4cabc8c1149b458b6
Version: 3f14b377d01d8357eba032b4cabc8c1149b458b6
Version: f5346df0591d10bc948761ca854b1fae6d2ef441
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/net/act_api.h",
            "net/sched/act_ct.c",
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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            "net/sched/act_ct.c",
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.203",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.167",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.130",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.77",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.18",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.203",
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                  "vulnerable": true
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                  "versionStartIncluding": "6.7.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks\n\nAs Paolo said earlier [1]:\n\n\"Since the blamed commit below, classify can return TC_ACT_CONSUMED while\nthe current skb being held by the defragmentation engine. As reported by\nGangMin Kim, if such packet is that may cause a UaF when the defrag engine\nlater on tries to tuch again such packet.\"\n\nact_ct was never meant to be used in the egress path, however some users\nare attaching it to egress today [2]. Attempting to reach a middle\nground, we noticed that, while most qdiscs are not handling\nTC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we\naddress the issue by only allowing act_ct to bind to clsact/ingress\nqdiscs and shared blocks. That way it\u0027s still possible to attach act_ct to\negress (albeit only with clsact).\n\n[1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/\n[2] https://lore.kernel.org/netdev/cc6bfb4a-4a2b-42d8-b9ce-7ef6644fb22b@ovn.org/"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-18T08:57:30.870Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bc4e5bb529823a09f02dbe96169de679a9db26e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb3c380a54e33d1fd272cc342faa906d787d7ef1"
        },
        {
          "url": "https://git.kernel.org/stable/c/5a110ddcc99bda77a28598b3555fe009eaab3828"
        },
        {
          "url": "https://git.kernel.org/stable/c/524ce8b4ea8f64900b6c52b6a28df74f6bc0801e"
        },
        {
          "url": "https://git.kernel.org/stable/c/380ad8b7c65ea7aa10ef2258297079ed5ac1f5b6"
        },
        {
          "url": "https://git.kernel.org/stable/c/9deda0fcda5c1f388c5e279541850b71a2ccfcf4"
        },
        {
          "url": "https://git.kernel.org/stable/c/11cb63b0d1a0685e0831ae3c77223e002ef18189"
        }
      ],
      "title": "net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23270",
    "datePublished": "2026-03-18T17:54:43.803Z",
    "dateReserved": "2026-01-13T15:37:45.991Z",
    "dateUpdated": "2026-04-18T08:57:30.870Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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