CVE-2026-63868 (GCVE-0-2026-63868)
Vulnerability from cvelistv5
Published
2026-07-19 14:18
Modified
2026-07-19 14:18
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net: garp: fix unsigned integer underflow in garp_pdu_parse_attr The receive-side GARP attribute parser computes dlen with reversed operands: dlen = sizeof(*ga) - ga->len; ga->len is the on-wire attribute length and includes the GARP attribute header. For normal attributes with data, ga->len is larger than sizeof(*ga), so the subtraction underflows in unsigned arithmetic. The resulting value is later passed to garp_attr_lookup(), whose length argument is u8. After truncation, the parsed data length usually no longer matches the length stored for locally registered attributes, so received Join/Leave events are ignored. This breaks the GARP receive path for common attributes, such as GVRP VLAN registration attributes. Compute the data length as the attribute length minus the header length.
References
Impacted products
Vendor Product Version
Linux Linux Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
Version: eca9ebac651f774d8b10fce7c5d173c3c3d3394f
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: garp: fix unsigned integer underflow in garp_pdu_parse_attr\n\nThe receive-side GARP attribute parser computes dlen with reversed\noperands:\n\n        dlen = sizeof(*ga) - ga-\u003elen;\n\nga-\u003elen is the on-wire attribute length and includes the GARP attribute\nheader. For normal attributes with data, ga-\u003elen is larger than\nsizeof(*ga), so the subtraction underflows in unsigned arithmetic.\n\nThe resulting value is later passed to garp_attr_lookup(), whose length\nargument is u8. After truncation, the parsed data length usually no\nlonger matches the length stored for locally registered attributes, so\nreceived Join/Leave events are ignored. This breaks the GARP receive path\nfor common attributes, such as GVRP VLAN registration attributes.\n\nCompute the data length as the attribute length minus the header length."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-19T14:18:37.823Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/16e408e607a94b646fb14a2a98422c6877ae4b3c"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-63868",
    "datePublished": "2026-07-19T14:18:37.823Z",
    "dateReserved": "2026-07-19T07:54:57.017Z",
    "dateUpdated": "2026-07-19T14:18:37.823Z",
    "state": "PUBLISHED"
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}


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