CVE-2023-53733 (GCVE-0-2023-53733)
Vulnerability from cvelistv5
Published
2025-10-24 11:44
Modified
2026-08-05 09:15
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: cls_u32: Undo tcf_bind_filter if u32_replace_hw_knode When u32_replace_hw_knode fails, we need to undo the tcf_bind_filter operation done at u32_set_parms.
References
Impacted products
Vendor Product Version
Linux Linux Version: d34e3e181395192d6d1f50dd97bd7854e04e33a4
Version: d34e3e181395192d6d1f50dd97bd7854e04e33a4
Version: d34e3e181395192d6d1f50dd97bd7854e04e33a4
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/cls_u32.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "a9345793469b65ee5ba7b033239916c2a67d3dd4",
              "status": "affected",
              "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4",
              "versionType": "git"
            },
            {
              "lessThan": "025159ed118ba5145b241d574edadb0e00d3c20f",
              "status": "affected",
              "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4",
              "versionType": "git"
            },
            {
              "lessThan": "9cb36faedeafb9720ac236aeae2ea57091d90a09",
              "status": "affected",
              "version": "d34e3e181395192d6d1f50dd97bd7854e04e33a4",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/sched/cls_u32.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.7"
            },
            {
              "lessThan": "4.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.42",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.4.*",
              "status": "unaffected",
              "version": "6.4.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.42",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.4.7",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.5",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: sched: cls_u32: Undo tcf_bind_filter if u32_replace_hw_knode\n\nWhen u32_replace_hw_knode fails, we need to undo the tcf_bind_filter\noperation done at u32_set_parms."
        }
      ],
      "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"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable path is reached through the rtnetlink `RTM_NEWTFILTER` interface (tc filter add/change) on the local system; no network peer can drive filter configuration. Packet transmission only serves to consume the corrupted state afterwards.\nAC:L - Failure of `u32_replace_hw_knode()` is fully attacker-controlled \u2014 setting the `skip_sw` flag on a filter attached to a non-offload-capable device (dummy/veth/lo) makes `tc_setup_cb_add()` return `-EOPNOTSUPP` deterministically on every attempt, with no race and no dependence on state outside the attacker\u0027s control.\nPR:L - Only `CAP_NET_ADMIN` within a network namespace is needed, which any unprivileged local user obtains with `unshare -Urn` before creating a dummy device, an HTB qdisc with classes, and u32 filters. Per kernel CNA guidance, tc/qdisc paths reachable via user namespaces are PR:L, not PR:H.\nUI:N - The attacker performs the entire sequence (create qdisc/class, repeatedly issue the failing filter add, delete the class, send traffic) unaided. No victim action is required at any point.\nS:U - The corrupted `filter_cnt` accounting and the resulting freed `htb_class` object both live in the kernel of the same machine, so the impact stays within a single security authority. This is standard kernel-local privilege escalation, not a hypervisor or IOMMU boundary crossing.\nC:H - The refcount imbalance permits a still-referenced traffic class to be freed while `res.class` remains a dangling pointer consumed by `htb_classify()`, giving a use-after-free on a slab object the attacker can reallocate and read back. Per guidance, a UAF that grants control over freed-object contents is High confidentiality impact.\nI:H - The same use-after-free lets a sprayed replacement object supply `cl-\u003elevel`, `cl-\u003eleaf.q` and the qdisc function pointers dereferenced in the enqueue path, yielding a write/control-flow-hijack primitive \u2014 the same primitive that produced working local privilege escalation for the sibling cls_u32 tcf_result bugs. Type-confused/UAF corruption of kernel objects is High integrity impact.\nA:H - Even without exploitation, the leaked `filter_cnt` permanently pins the class and its qdisc so `tc class del` always returns `-EBUSY` and the memory is never reclaimed, and the dangling `res.class` dereference in the packet enqueue path oopses the kernel. Any kernel crash or use-after-free is High availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:15:44.713Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a9345793469b65ee5ba7b033239916c2a67d3dd4"
        },
        {
          "url": "https://git.kernel.org/stable/c/025159ed118ba5145b241d574edadb0e00d3c20f"
        },
        {
          "url": "https://git.kernel.org/stable/c/9cb36faedeafb9720ac236aeae2ea57091d90a09"
        }
      ],
      "title": "net: sched: cls_u32: Undo tcf_bind_filter if u32_replace_hw_knode",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2023-53733",
    "datePublished": "2025-10-24T11:44:28.115Z",
    "dateReserved": "2025-10-22T13:21:37.350Z",
    "dateUpdated": "2026-08-05T09:15:44.713Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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