{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-53751",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-53751"
  ],
  "published": "2025-12-08T01:19:54Z",
  "summary": "cifs: fix potential use-after-free bugs in TCP_Server_Info::hostname",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix potential use-after-free bugs in TCP_Server_Info::hostname\n\nTCP_Server_Info::hostname may be updated once or many times during\nreconnect, so protect its access outside reconnect path as well and\nthen prevent any potential use-after-free bugs.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/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": "6.1.28"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-53751"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/64d62ac6d6514cba1305bd08e271ec1843bdd612"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c511954bf142fe1995aec3c739a9f1a76990283a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0b08c4c499200be67d54c439d56e5ea866869945"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/90c49fce1c43e1cc152695e20363ff5087897c09"
    }
  ],
  "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": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - The vulnerability is in the CIFS/SMB client's handling of remote server data \u2014 the freed/reallocated `hostname` is derived from server-supplied DFS referral targets, and both the free side (forced reconnects) and the read side (error-path `cifs_server_dbg(VFS,...)` on malformed or bad-signature responses) are driven entirely by a remote SMB peer or an on-path network attacker.\nAC:L - The attacker controls both sides of the race: it can force unlimited reconnect cycles by dropping the TCP connection, chooses DFS target names so it controls the size and content of the freed/reallocated string for heap grooming, and can trigger the unlocked readers on demand via malformed responses, with unlimited retries.\nPR:N - No credentials or privileges on the target are required \u2014 the attacker is the remote SMB server or a network attacker, and the reader side is additionally reachable by any unprivileged local user through the world-readable (0444) /proc/fs/cifs/DebugData and 0644 /proc/fs/cifs/Stats.\nUI:N - Against a host with an already-established DFS CIFS mount (routine on enterprise servers and appliances), the attacker triggers reconnects and error paths on its own; no action by any user is needed at attack time.\nS:U - The use-after-free is in kernel memory and its impact stays within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `seq_printf(\"%s\", server->hostname)` on the dangling pointer copies freed heap memory into the world-readable /proc/fs/cifs/DebugData output, reading until an arbitrary NUL byte, giving an unbounded kernel heap disclosure whose contents the attacker can groom; the same data also leaks to dmesg via `cifs_server_dbg`.\nI:H - This is a use-after-free on an attacker-size-controlled slab object with a racing free/reassign of the same pointer, which enables heap spraying and reclaim of the freed slot; per kernel UAF scoring this is treated as exploitable for control-flow/memory corruption.\nA:H - Dereferencing the freed string over poisoned, unmapped, or reallocated memory produces a kernel oops/panic, and the attacker can repeat the reconnect-driven race indefinitely."
    }
  }
}