{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-74436",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-74436"
  ],
  "published": "2026-08-15T06:04:33Z",
  "summary": "rxrpc: serialize kernel accept preallocation with socket teardown",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: serialize kernel accept preallocation with socket teardown\n\nrxrpc_kernel_charge_accept() reads rx->backlog without any\nsocket/backlog synchronization and passes that raw pointer into\nrxrpc_service_prealloc_one(). A concurrent rxrpc_discard_prealloc()\nsets rx->backlog = NULL and frees the backlog rings, so a kernel\npreallocation worker can keep using a freed struct rxrpc_backlog\nwhile updating *_backlog_head/tail and array slots.\n\nSerialize the state check and backlog lookup with the socket lock,\nand reject kernel preallocation once teardown has disabled\nlistening or discarded the service backlog.",
  "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": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.184",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-74436"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d6207326b4ca0ae1041281b6af9df53f8080669a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/11b429b84c87cb5a0152f14e7d6cb649ed363901"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c20d983968f239574290cf804a58cde18ad1c559"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0337cdba0c477f176c0459bed012109453184573"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/dfa0b2bbc5e50119f89c6b5407faa5ed86dfa7c5"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/35a967ff8b24db09ee429c39c5b5e6571639997d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1741378a7a83dfd8e53a9196730df709b903cd33"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/dc175389b18c29a5303ee83169ec653adfae3e17"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-23T12:46:35Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - RxRPC is a UDP network protocol; remote peers can send packets to AFS callback-manager listeners (port 7001) that instantiate incoming calls and queue kernel preallocation work reaching rxrpc_kernel_charge_accept().\nAC:L - The attacker controls the preallocation side by flooding concurrent rxrpc/AFS callback traffic while a peer thread tears down the same socket via listen(0), shutdown, or close during AFS netns exit, creating a winnable race.\nPR:N - No local account, capability, or authentication is required to reach the vulnerable preallocation path; any remote host that can deliver rxrpc/UDP packets to a listening AFS callback manager can drive the charge_accept worker.\nUI:N - Exploitation requires no victim interaction beyond normal background AFS service operation; the attacker triggers the bug purely through network traffic timed against automatic or administrative socket teardown.\nS:U - The use-after-free corrupts kernel heap metadata and rxrpc backlog structures within kernel memory, enabling local privilege escalation but not crossing a VM, container, or IOMMU security boundary by itself.\nC:H - Concurrent use of a freed struct rxrpc_backlog allows reads and corruption of recycled slab memory, providing a standard kmalloc UAF primitive that can leak kernel pointers and sensitive data.\nI:H - The race writes peer, connection, and call pointers plus head/tail indices into freed backlog ring slots, enabling heap grooming and arbitrary kernel memory corruption exploitable for code execution.\nA:H - Use-after-free on the backlog structure during concurrent head/tail and pointer-array updates can cause kernel oops, panic, or hang, and repeated triggering enables sustained denial of service."
    }
  }
}