CVE-2026-64047 (GCVE-0-2026-64047)
Vulnerability from cvelistv5
Published
2026-07-19 15:39
Modified
2026-08-05 12:38
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring When an sk_msg scatterlist ring wraps (sg.end < sg.start), tls_push_record() chains the tail portion of the ring to the head using sg_chain(). An extra entry in the sg array is reserved for this: struct sk_msg_sg { [...] /* The extra two elements: * 1) used for chaining the front and sections when the list becomes * partitioned (e.g. end < start). The crypto APIs require the * chaining; * 2) to chain tailer SG entries after the message. */ struct scatterlist data[MAX_MSG_FRAGS + 2]; The current code uses MAX_SKB_FRAGS + 1 as the ring size: sg_chain(&msg_pl->sg.data[msg_pl->sg.start], MAX_SKB_FRAGS - msg_pl->sg.start + 1, msg_pl->sg.data); This places the chain pointer at sg_chain(data[start], (MAX_SKB_FRAGS - msg_start + 1) .. = &data[start] + (MAX_SKB_FRAGS - msg_start + 1) - 1 = data[start + (MAX_SKB_FRAGS - start + 1) - 1] = data[MAX_SKB_FRAGS] instead of the true last entry. This is likely due to a "race" of the commit under Fixes landing close to commit 031097d9e079 ("bpf: sk_msg, zap ingress queue on psock down") Convert to ARRAY_SIZE and drop the data[start] / - start (as suggested by Sabrina).
References
Impacted products
Vendor Product Version
Linux Linux Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: 9aaaa56845a06aeabdd597cbe19492dc01f281ec
Version: d529d6c9f7e3aaeac13c4948f79799ccb825f29d
Version: 5.4.14   ≤
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/tls/tls_sw.c"
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      ],
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              "negate": false,
              "operator": "OR"
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring\n\nWhen an sk_msg scatterlist ring wraps (sg.end \u003c sg.start),\ntls_push_record() chains the tail portion of the ring to the head\nusing sg_chain(). An extra entry in the sg array is reserved for\nthis:\n\n  struct sk_msg_sg {\n        [...]\n        /* The extra two elements:\n         * 1) used for chaining the front and sections when the list becomes\n         *    partitioned (e.g. end \u003c start). The crypto APIs require the\n         *    chaining;\n         * 2) to chain tailer SG entries after the message.\n         */\n        struct scatterlist              data[MAX_MSG_FRAGS + 2];\n\nThe current code uses MAX_SKB_FRAGS + 1 as the ring size:\n\n    sg_chain(\u0026msg_pl-\u003esg.data[msg_pl-\u003esg.start],\n             MAX_SKB_FRAGS - msg_pl-\u003esg.start + 1,\n             msg_pl-\u003esg.data);\n\nThis places the chain pointer at\n\n  sg_chain(data[start], (MAX_SKB_FRAGS - msg_start + 1) .. =\n  \u0026data[start] + (MAX_SKB_FRAGS - msg_start + 1) - 1 =\n  data[start + (MAX_SKB_FRAGS - start + 1) - 1] =\n  data[MAX_SKB_FRAGS]\n\ninstead of the true last entry. This is likely due to a \"race\" of\nthe commit under Fixes landing close to\ncommit 031097d9e079 (\"bpf: sk_msg, zap ingress queue on psock down\")\n\nConvert to ARRAY_SIZE and drop the data[start] / - start (as suggested\nby Sabrina)."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The flaw is in kernel TLS (kTLS) software transmit encryption triggered when a TLS socket sends records; remote peers on established TLS connections drive this TX path through normal network I/O.\nAC:L - An attacker who controls connection traffic can reliably create the wrapped sk_msg ring state via BPF sockmap SK_MSG verdict helpers (push/pop/redirect) and then trigger record push on demand.\nPR:N - Exploitation requires no privileges on the target host beyond being a network peer on a kTLS socket with sockmap BPF already configured by the service; attacker capabilities are not needed on the victim system.\nUI:N - Triggering requires only automated server-side TLS transmit activity in response to network input, with no victim user action.\nS:U - Impact is kernel memory corruption and potential privilege escalation within the same kernel/host security boundary, not a cross-VM or sandbox escape by itself.\nC:H - Corrupting an active scatterlist entry causes the AEAD crypto path to follow an incorrect chain, enabling out-of-bounds kernel memory reads beyond intended plaintext buffers.\nI:H - The malformed scatterlist passed to crypto_aead_encrypt() can direct encryption I/O to wrong memory regions, providing an out-of-bounds write primitive exploitable for control-flow hijacking.\nA:H - Scatterlist corruption in the kernel crypto TX path can cause kernel oopses, panics, or fatal BUG conditions when invalid chain entries or page pointers are dereferenced."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:38:39.300Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/73963a375885d5ccb7def39fd0b4f542e0f343dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/47110c3a9ac247b688657337f5981efcfcb240dc"
        },
        {
          "url": "https://git.kernel.org/stable/c/84158c2997159df4a0d70cd9c46774512d32a522"
        },
        {
          "url": "https://git.kernel.org/stable/c/131ef12057d92b77b636321b7849c69222405a97"
        },
        {
          "url": "https://git.kernel.org/stable/c/66339b71f105e6f83e0da3b9583d95077534fe1d"
        },
        {
          "url": "https://git.kernel.org/stable/c/eca989eab4b2599dcb02f72140a7c08f08838520"
        },
        {
          "url": "https://git.kernel.org/stable/c/2fb0dc7e0099686c4e9d2732745d8a31b18c3628"
        },
        {
          "url": "https://git.kernel.org/stable/c/285943c6e7ca309bbea84b253745154241d9788a"
        }
      ],
      "title": "net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64047",
    "datePublished": "2026-07-19T15:39:31.960Z",
    "dateReserved": "2026-07-19T07:54:57.029Z",
    "dateUpdated": "2026-08-05T12:38:39.300Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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