CVE-2026-99112 (GCVE-0-2026-99112)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34
VLAI
Title
net/sched: cls_flower: validate mask pointer after nla_next()
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_flower: validate mask pointer after nla_next() fl_set_enc_opt() iterates the key's nested tunnel-option attributes with nla_for_each_attr() while advancing a single mask pointer via nla_next() at the bottom of each loop, so the mask cursor is driven by the number of key attributes rather than by the mask's own attributes. The nla_ok() added by commit c96adff956191 ("cls_flower: call nla_ok() before nla_next()") only validates the mask pointer that was just consumed; the pointer produced by nla_next() is used by the next iteration (fl_set_geneve_opt() and siblings) without any validation. The mask's nested attributes are validated with NL_VALIDATE_LIBERAL, which merely warns on trailing bytes that do not form a complete attribute. A mask carrying one valid attribute plus 1-3 residue bytes (or a non-aligned attribute length making msk_depth negative) therefore reaches the next iteration with msk_depth != 0, so neither the !msk_depth check in fl_set_enc_opt() nor the !depth check in the per-type helpers fires. nla_type() then reads past the mask payload and nla_parse_nested_deprecated() iterates with an nla_len taken from those bytes, reading well beyond the mask attribute (KASAN: slab-out-of-bounds read in __nla_validate_parse from fl_change()). Validate the advanced mask pointer as well: when the mask is not legitimately exhausted (msk_depth != 0) and the new pointer fails nla_ok(), reject the filter with -EINVAL. An exactly exhausted mask still skips the check, preserving exact-match behaviour for the remaining key attributes.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c96adff95619178e2118925578343ad54857c80c , < 45e60747a9db2307929260d9aa9c1c6cbb70ee77 (git)
Affected: c96adff95619178e2118925578343ad54857c80c , < bb187146c7e5c666874784e4f3fc1bc5126e6e92 (git)
Affected: c96adff95619178e2118925578343ad54857c80c , < fee10655709c5c597e8e9f722f3035d9ea31ff3a (git)
Affected: 238b5ebdb6a6e4bc90810b9f8ec0063b3dfda41a (git)
Affected: 5.10.11 , < 5.11 (semver)
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Linux Linux Affected: 5.11
Unaffected: 0 , < 5.11 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
  "containers": {
    "cna": {
      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/cls_flower.c"
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          "vendor": "Linux",
          "versions": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_flower: validate mask pointer after nla_next()\n\nfl_set_enc_opt() iterates the key\u0027s nested tunnel-option attributes\nwith nla_for_each_attr() while advancing a single mask pointer via\nnla_next() at the bottom of each loop, so the mask cursor is driven\nby the number of key attributes rather than by the mask\u0027s own\nattributes.  The nla_ok() added by commit c96adff956191 (\"cls_flower:\ncall nla_ok() before nla_next()\") only validates the mask pointer\nthat was just consumed; the pointer produced by nla_next() is used by\nthe next iteration (fl_set_geneve_opt() and siblings) without any\nvalidation.\n\nThe mask\u0027s nested attributes are validated with NL_VALIDATE_LIBERAL,\nwhich merely warns on trailing bytes that do not form a complete\nattribute.  A mask carrying one valid attribute plus 1-3 residue\nbytes (or a non-aligned attribute length making msk_depth negative)\ntherefore reaches the next iteration with msk_depth != 0, so neither\nthe !msk_depth check in fl_set_enc_opt() nor the !depth check in the\nper-type helpers fires.  nla_type() then reads past the mask payload\nand nla_parse_nested_deprecated() iterates with an nla_len taken\nfrom those bytes, reading well beyond the mask attribute (KASAN:\nslab-out-of-bounds read in __nla_validate_parse from fl_change()).\n\nValidate the advanced mask pointer as well: when the mask is not\nlegitimately exhausted (msk_depth != 0) and the new pointer fails\nnla_ok(), reject the filter with -EINVAL.  An exactly exhausted mask\nstill skips the check, preserving exact-match behaviour for the\nremaining key attributes."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:29.881Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/fee10655709c5c597e8e9f722f3035d9ea31ff3a"
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      "title": "net/sched: cls_flower: validate mask pointer after nla_next()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99112",
    "datePublished": "2026-10-28T10:34:29.881Z",
    "dateReserved": "2026-09-25T10:25:14.392Z",
    "dateUpdated": "2026-10-28T10:34:29.881Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-10-29",
      "epss": "0.00174",
      "percentile": "0.06865"
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      "cve": "CVE-2026-99112",
      "id": "msrc_CVE-2026-99112",
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "net/sched: cls_flower: validate mask pointer after nla_next()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-99112.json",
      "version": "1"
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        "descriptions": [
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_flower: validate mask pointer after nla_next()\n\nfl_set_enc_opt() iterates the key\u0027s nested tunnel-option attributes\nwith nla_for_each_attr() while advancing a single mask pointer via\nnla_next() at the bottom of each loop, so the mask cursor is driven\nby the number of key attributes rather than by the mask\u0027s own\nattributes.  The nla_ok() added by commit c96adff956191 (\"cls_flower:\ncall nla_ok() before nla_next()\") only validates the mask pointer\nthat was just consumed; the pointer produced by nla_next() is used by\nthe next iteration (fl_set_geneve_opt() and siblings) without any\nvalidation.\n\nThe mask\u0027s nested attributes are validated with NL_VALIDATE_LIBERAL,\nwhich merely warns on trailing bytes that do not form a complete\nattribute.  A mask carrying one valid attribute plus 1-3 residue\nbytes (or a non-aligned attribute length making msk_depth negative)\ntherefore reaches the next iteration with msk_depth != 0, so neither\nthe !msk_depth check in fl_set_enc_opt() nor the !depth check in the\nper-type helpers fires.  nla_type() then reads past the mask payload\nand nla_parse_nested_deprecated() iterates with an nla_len taken\nfrom those bytes, reading well beyond the mask attribute (KASAN:\nslab-out-of-bounds read in __nla_validate_parse from fl_change()).\n\nValidate the advanced mask pointer as well: when the mask is not\nlegitimately exhausted (msk_depth != 0) and the new pointer fails\nnla_ok(), reject the filter with -EINVAL.  An exactly exhausted mask\nstill skips the check, preserving exact-match behaviour for the\nremaining key attributes."
          }
        ],
        "id": "CVE-2026-99112",
        "lastModified": "2026-10-28T11:17:30.640",
        "metrics": {},
        "published": "2026-10-28T11:17:30.640",
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        "vulnStatus": "Received"
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      "current_release_date": "2026-10-29T07:53:04+00:00",
      "cve": "CVE-2026-99112",
      "id": "CVE-2026-99112",
      "initial_release_date": "2026-10-28T00:00:00+00:00",
      "product_status:known_affected": "236",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: cls_flower: validate mask pointer after nla_next()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99112.json",
      "version": "3"
    }
  }
}



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