{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2023-53566",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2023-53566"
  ],
  "published": "2025-10-04T15:17:41Z",
  "summary": "netfilter: nft_set_rbtree: fix null deref on element insertion",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_set_rbtree: fix null deref on element insertion\n\nThere is no guarantee that rb_prev() will not return NULL in nft_rbtree_gc_elem():\n\ngeneral protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN\nKASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]\n nft_add_set_elem+0x14b0/0x2990\n  nf_tables_newsetelem+0x528/0xb30\n\nFurthermore, there is a possible use-after-free while iterating,\n'node' can be free'd so we need to cache the next value to use.",
  "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": "6.1.30"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-53566"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b76db53ee8802ee5683f8cb401d7e2ec6f9b3d56"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/899aa5638568abf5d69de7a7bb95e4615157375b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3fa13203b6d90cc3a33af47b058739f92ab82eef"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ec5caa765f7f6960011c919c9aeb1467940421f6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a836be60a3aabcedcd9c79f545d409ace1f20ba6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a337706c1fb35aac3f26b48aca80421bdbe1d33a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/61ae320a29b0540c16931816299eb86bf2b66c08"
    }
  ],
  "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 is reached only through the nfnetlink/nftables netlink socket (NFT_MSG_NEWSETELEM), which requires local system access; there is no packet-processing path into nft_rbtree_gc_elem().\nAC:L - The attacker fully controls set contents, element timeouts, and insertion order, so making an expired element the leftmost rbtree node (rb_prev() == NULL) during the overlap walk is deterministic and needs no race or unpredictable memory layout.\nPR:L - Only CAP_NET_ADMIN in the network namespace is required, enforced via namespace-relative netlink_net_capable(), which any unprivileged user obtains with \"unshare -Urn\"; nftables and the rbtree set backend are fully netns-aware and autoloaded.\nUI:N - The attacker triggers the bug entirely from their own process by issuing netlink set-element operations; no victim action is involved.\nS:U - The corruption and crash occur within the kernel of the same host and security authority as the attacking task, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The fix addresses a use-after-free during the tree walk (an rb_erase()'d, RCU-freed element is re-entered via rb_next()), and a UAF/double-free of nft_rbtree_elem objects gives the attacker control over reclaimed slab contents and thus a kernel memory read primitive.\nI:H - Beyond the crash, rb_erase() is invoked on an unvalidated rbe_prev (NULL or a wrong still-active element) and on already-erased nodes, producing attacker-influenced rbtree pointer writes and double nft_set_elem_destroy() \u2014 a classic heap-corruption primitive usable for control-flow hijack.\nA:H - The documented and readily reproducible outcome is a general protection fault / null-ptr-deref oops inside nft_add_set_elem() while holding the rbtree write lock and nftables commit mutex, panicking the kernel or wedging the netfilter subsystem."
    }
  }
}