CVE-2026-74659 (GCVE-0-2026-74659)
Vulnerability from cvelistv5
Published
2026-08-22 15:32
Modified
2026-08-22 15:32
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net: bridge: mrp: fix uninitialised bytes on the wire br_mrp_alloc_test_skb() builds MRP test frames on an skb from dev_alloc_skb(), which does not clear the linear data area. On the MRA ring-role branch the sub-option TLV header is appended with sub_tlv = skb_put(skb, sizeof(*sub_tlv)); sub_tlv->type = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR; so sub_tlv->length is never written, and the two trailing alignment bytes are appended with a bare skb_put() that does not clear them either. The neighbouring oui and sub_opt regions are explicitly zeroed, so three uninitialised bytes are left in every MRA MRP_Test frame that goes out. Put the sub-option TLV header and the alignment padding in a single skb_put_zero(), which clears both. The AUTO_MGR sub-TLV carries no payload, so the zeroed length field is already the value it should have.
References
Impacted products
Vendor Product Version
Linux Linux Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
Version: f7458934b0791c39a001e4d902fc3bf697b439b5
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{
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          "programFiles": [
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              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: mrp: fix uninitialised bytes on the wire\n\nbr_mrp_alloc_test_skb() builds MRP test frames on an skb from\ndev_alloc_skb(), which does not clear the linear data area.  On the MRA\nring-role branch the sub-option TLV header is appended with\n\n\tsub_tlv = skb_put(skb, sizeof(*sub_tlv));\n\tsub_tlv-\u003etype = BR_MRP_SUB_TLV_HEADER_TEST_AUTO_MGR;\n\nso sub_tlv-\u003elength is never written, and the two trailing alignment bytes\nare appended with a bare skb_put() that does not clear them either.  The\nneighbouring oui and sub_opt regions are explicitly zeroed, so three\nuninitialised bytes are left in every MRA MRP_Test frame that goes out.\n\nPut the sub-option TLV header and the alignment padding in a single\nskb_put_zero(), which clears both.  The AUTO_MGR sub-TLV carries no\npayload, so the zeroed length field is already the value it should have."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-22T15:32:32.926Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/014c062d23c63ec77ef2cf17a0d9363c7441cc94"
        },
        {
          "url": "https://git.kernel.org/stable/c/7ebc23ff03668042e0b0e4034bb1518d36198d9e"
        },
        {
          "url": "https://git.kernel.org/stable/c/06d58b8d2f053ced82e01efaeb6e7c82891eed58"
        },
        {
          "url": "https://git.kernel.org/stable/c/a5e385eeb2d6dbbbdebfa050e67c34734ae12693"
        },
        {
          "url": "https://git.kernel.org/stable/c/5912cf1822fbe53ae275c147868740eb384a5d3e"
        },
        {
          "url": "https://git.kernel.org/stable/c/e08665218040f8e312abe40f74543186f3c2c941"
        },
        {
          "url": "https://git.kernel.org/stable/c/63488dba65ef91373ef616575b32eb0eb21459f4"
        }
      ],
      "title": "net: bridge: mrp: fix uninitialised bytes on the wire",
      "x_generator": {
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    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74659",
    "datePublished": "2026-08-22T15:32:32.926Z",
    "dateReserved": "2026-08-15T05:44:03.924Z",
    "dateUpdated": "2026-08-22T15:32:32.926Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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