GHSA-76W3-FGP7-3HF7

Vulnerability from github – Published: 2026-05-06 12:30 – Updated: 2026-05-12 21:31
VLAI?
Details

In the Linux kernel, the following vulnerability has been resolved:

net/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash()

Commit 38a6f0865796 ("net: sched: support hash selecting tx queue") added SKBEDIT_F_TXQ_SKBHASH support. The inclusive range size is computed as:

mapping_mod = queue_mapping_max - queue_mapping + 1;

The range size can be 65536 when the requested range covers all possible u16 queue IDs (e.g. queue_mapping=0 and queue_mapping_max=U16_MAX). That value cannot be represented in a u16 and previously wrapped to 0, so tcf_skbedit_hash() could trigger a divide-by-zero:

queue_mapping += skb_get_hash(skb) % params->mapping_mod;

Compute mapping_mod in a wider type and reject ranges larger than U16_MAX to prevent params->mapping_mod from becoming 0 and avoid the crash.

Severity ?
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-43238"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-369"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-06T12:16:44Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_skbedit: fix divide-by-zero in tcf_skbedit_hash()\n\nCommit 38a6f0865796 (\"net: sched: support hash selecting tx queue\")\nadded SKBEDIT_F_TXQ_SKBHASH support. The inclusive range size is\ncomputed as:\n\nmapping_mod = queue_mapping_max - queue_mapping + 1;\n\nThe range size can be 65536 when the requested range covers all possible\nu16 queue IDs (e.g. queue_mapping=0 and queue_mapping_max=U16_MAX).\nThat value cannot be represented in a u16 and previously wrapped to 0,\nso tcf_skbedit_hash() could trigger a divide-by-zero:\n\nqueue_mapping += skb_get_hash(skb) % params-\u003emapping_mod;\n\nCompute mapping_mod in a wider type and reject ranges larger than U16_MAX\nto prevent params-\u003emapping_mod from becoming 0 and avoid the crash.",
  "id": "GHSA-76w3-fgp7-3hf7",
  "modified": "2026-05-12T21:31:26Z",
  "published": "2026-05-06T12:30:34Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43238"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/015cebdfcb97b5347fb7f598ea712a281cb35840"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3c2b95b26860bd6f8e2310d31ea1200d3f8f173e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4ece5eb4836f8ff03b9004dc2430a7169f282851"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/59809fda4da7730cfe84a948033f47eb45db073d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9c735a7d98c982a786b0db71eb6566ee00aaa04f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/be054cc66f739a9ba615dba9012a07fab8e7dd6f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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