CVE-2026-98493 (GCVE-0-2026-98493)
Vulnerability from cvelistv5
Published
2026-10-18 15:16
Modified
2026-10-30 12:38
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net: ipconfig: bound DHCP option construction ic_dhcp_init_options() appends the hostname (option 12), vendor-class (option 60) and client-ID (option 61) options into the fixed 312-byte bootp_pkt.exten[] buffer. Only the client-ID branch checked the remaining space; the hostname and vendor-class writes were unbounded. A 64-byte hostname together with the maximum 252-byte dhcpclass= identifier needs 18 + (2 + 64) + (2 + 252) = 338 of the 312 available bytes even before the terminating END marker, so the vendor-class memcpy runs past the end of exten[]. With CONFIG_FORTIFY_SOURCE this is reported as a field-spanning write and, when the kernel is booted with panic_on_warn=1, aborts boot with a panic. Route the optional options through a common helper that makes sure the option, its 2-byte header and the END marker all fit and drops an option that would not. Configurations with short options keep sending exactly the same bytes as before.
References
Impacted products
Vendor Product Version
Linux Linux Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
Version: 130c0f47fdf9c533deb1136cad5136f6cb7020f0
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{
  "containers": {
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          "product": "Linux",
          "programFiles": [
            "net/ipv4/ipconfig.c"
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      ],
      "cpeApplicability": [
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              "negate": false,
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipconfig: bound DHCP option construction\n\nic_dhcp_init_options() appends the hostname (option 12), vendor-class\n(option 60) and client-ID (option 61) options into the fixed 312-byte\nbootp_pkt.exten[] buffer.  Only the client-ID branch checked the\nremaining space; the hostname and vendor-class writes were unbounded.\n\nA 64-byte hostname together with the maximum 252-byte dhcpclass=\nidentifier needs 18 + (2 + 64) + (2 + 252) = 338 of the 312 available\nbytes even before the terminating END marker, so the vendor-class memcpy\nruns past the end of exten[].  With CONFIG_FORTIFY_SOURCE this is\nreported as a field-spanning write and, when the kernel is booted with\npanic_on_warn=1, aborts boot with a panic.\n\nRoute the optional options through a common helper that makes sure the\noption, its 2-byte header and the END marker all fit and drops an option\nthat would not.  Configurations with short options keep sending exactly\nthe same bytes as before."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:38:18.516Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e0a221cec0e0ee437680ae0314a4b166509442c5"
        },
        {
          "url": "https://git.kernel.org/stable/c/ca811550b9fa87e02845b4a332d194c2304d933f"
        },
        {
          "url": "https://git.kernel.org/stable/c/d8016c82acdd7eaa462e1f38a962b15d8c6a650b"
        },
        {
          "url": "https://git.kernel.org/stable/c/38a6a118260ebfc82d0c653194d616bdfbd236ac"
        },
        {
          "url": "https://git.kernel.org/stable/c/abcba6f080c63e403037ecdffde43170d242376a"
        },
        {
          "url": "https://git.kernel.org/stable/c/24e79508b237dd2a69bc6fb6ac5cf7f126178307"
        },
        {
          "url": "https://git.kernel.org/stable/c/cbaad2922bd5d4d303055ae9afecc8999e6b40c9"
        },
        {
          "url": "https://git.kernel.org/stable/c/e47a1958e12abc3a17b5231a4f21c8f1bf662e08"
        }
      ],
      "title": "net: ipconfig: bound DHCP option construction",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98493",
    "datePublished": "2026-10-18T15:16:22.301Z",
    "dateReserved": "2026-09-25T10:25:14.353Z",
    "dateUpdated": "2026-10-30T12:38:18.516Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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