{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-74628",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-74628"
  ],
  "published": "2026-08-22T15:32:12Z",
  "summary": "net/x25: fix use-after-free of the socket by its timers",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/x25: fix use-after-free of the socket by its timers\n\nThe x25 timers are armed with mod_timer() and cancelled with\ntimer_delete(), so a pending timer holds no reference on the socket and a\ncancel does not wait for a callback already running on another CPU.\n\nx25_heartbeat_expiry() also rearms unconditionally, so it can reinstall\nsk->sk_timer after __x25_destroy_socket() has passed its cancel point.\nThe following __sock_put() frees the socket while the timer is still\nqueued, and the next expiry uses freed memory.  KASAN reports a\nslab-use-after-free on the kmalloc-2k object freed by close().\n\ntimer_delete_sync() cannot be used here: x25_heartbeat_expiry() and\nx25_timer_expiry() both reach the cancels from inside the timer they\nwould wait on, through __x25_destroy_socket() and x25_disconnect().\n\nArm the timers with sk_reset_timer() and cancel them with sk_stop_timer()\nso that an armed timer owns a reference, and release it in both expiry\nhandlers.  Rearm the heartbeat only while sk_hashed(sk) is still true,\nsince __x25_destroy_socket() unlinks the socket before dropping it.  Arm\nthe deferred destroy timer the same way and drop its reference in\nx25_destroy_timer().\n\nReproduced on net with KASAN, with the heartbeat period shortened so the\nwindow recurs.  With this patch the reproducer no longer triggers a\nreport and /proc/net/x25 drains.\n\nDiscovered by XBOW, triaged by Baul Lee <baul.lee@xbow.com>",
  "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-2026-74628"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ba925a2e98ce967a0e71c5bcbcf5dbd3facaf0c8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6b79659590f0f82a9b8efd2ffd55ec6399ebfc33"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/fdd9ac50b9b61ef2b2d52c5156aff788be91454d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1fc9f6d2c7c9fdb341bfe8ca449c990632299ea6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3c4919be5d910db4beebca420953858606fba7d8"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/4bc522b33438fefc3272840ae5988771863a4f1f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e92c7e2b41d1528a830bc64c5e4e46dfa8133dda"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/2195424c3da2ef1829a63b807e3a900a90e57d85"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-27T12:40:42Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 9.8,
      "cvss_v3_severity": "Critical",
      "scenario": "AV:N - Remote X.25 frames reach x25_lapb_receive_frame() on init_net gateways, where unauthenticated CALL_REQUEST/CLEAR handling arms heartbeat timers and drives server socket teardown through __x25_destroy_socket() during close.\nAC:L - The attacker controls both sides of the race by opening/closing sockets or sending concurrent connect/clear traffic, repeatedly forcing __x25_destroy_socket() against sk_timer callbacks that re-arm via mod_timer().\nPR:N - X.25 call setup and clearing are unauthenticated on the wire; a remote peer can create sockets via CALL_REQUEST and force teardown without any local account or CAP_NET_ADMIN.\nUI:N - Exploitation requires no end-user action; automated server handling of remote X.25 connect/clear suffices to reach the vulnerable close/timer path.\nS:U - Impact stays within kernel memory via standard slab UAF on the AF_X25 socket object; this is not a guest/host or IOMMU boundary escape.\nC:H - KASAN reports slab-use-after-free on the kmalloc-2k socket freed by close(), and UAF on struct sock gives attacker-controlled reuse enabling arbitrary kernel memory disclosure.\nI:H - Use-after-free of the socket structure enables heap grooming and corrupting freed object contents for control-flow or arbitrary kernel writes/code execution.\nA:H - The freed socket timer expiry dereferences released memory and can oops/panic the kernel; UAF reliably threatens system availability even before full exploitation."
    }
  }
}