{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-53669",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-53669"
  ],
  "published": "2025-10-07T15:23:56Z",
  "summary": "tcp: fix skb_copy_ubufs() vs BIG TCP",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix skb_copy_ubufs() vs BIG TCP\n\nDavid Ahern reported crashes in skb_copy_ubufs() caused by TCP tx zerocopy\nusing hugepages, and skb length bigger than ~68 KB.\n\nskb_copy_ubufs() assumed it could copy all payload using up to\nMAX_SKB_FRAGS order-0 pages.\n\nThis assumption broke when BIG TCP was able to put up to 512 KB per skb.\n\nWe did not hit this bug at Google because we use CONFIG_MAX_SKB_FRAGS=45\nand limit gso_max_size to 180000.\n\nA solution is to use higher order pages if needed.\n\nv2: add missing __GFP_COMP, or we leak memory.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.21-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v6",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v8",
            "binary_version": "1:6.1.21-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.21-1+rpt1": {
            "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed",
            "upstream_version": "6.1.21",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.29"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-53669"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7fa93e39fbb0566019c388a8038a4d58552e0910"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3c77a377877acbaf03cd7caa21d3644a5dd16301"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9cd62f0ba465cf647c7d8c2ca7b0d99ea0c1328f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7e692df3933628d974acb9f5b334d2b3e885e2a6"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:24:39Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerable code only runs on locally-originated TX skbs carrying MSG_ZEROCOPY frags; received network packets never carry zcopy frags (skb_zcopy() is false, early return), so a remote peer cannot reach it. Triggering requires local socket/syscall activity.\nAC:L - The local attacker controls every precondition \u2014 enabling BIG TCP (CAP_NET_ADMIN via user namespace on a private netns device), using THP/hugepage-backed buffers, and sending MSG_ZEROCOPY payloads sized to overflow \u2014 so the overflow is reliably reproducible.\nPR:L - Exploitation requires running local code (MSG_ZEROCOPY sendmsg) and CAP_NET_ADMIN to raise gso_max_size, both available to a basic unprivileged user through an unprivileged user+network namespace. No real root is needed.\nUI:N - The attacker triggers the overflow entirely through its own socket operations; no action by another user is required.\nS:U - The out-of-bounds write corrupts kernel heap within the same kernel security authority; there is no crossing of a VM/IOMMU/sandbox boundary.\nC:H - The OOB write corrupts skb_shared_info frag page descriptors, which can be steered so kernel data is read/transmitted from attacker-influenced pages, and per guidance memory corruption leveragable for disclosure scores High.\nI:H - This is a controllable-size out-of-bounds heap write (frag descriptors written past the frags array), providing a write primitive suitable for control-flow hijacking or privilege escalation.\nA:H - The overflow reliably corrupts adjacent memory and was reported as causing kernel crashes (oops/panic), a full denial of service."
    }
  }
}