{
  "cveId": "CVE-2026-23294",
  "url": "https://patchblox.com/security/cve/CVE-2026-23294",
  "summary": "CVE-2026-23294 is fixed in 23 products on 1 platform, first by DEBIAN-CVE-2026-23294, released March 25, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "linux: In the Linux kernel, the following vulnerability has been resolved:  bpf: Fix race in devmap on PREEMPT_RT  On PREEMP...",
  "description": "In the Linux kernel, the following vulnerability has been resolved:  bpf: Fix race in devmap on PREEMPT_RT  On PREEMPT_RT kernels, the per-CPU xdp_dev_bulk_queue (bq) can be accessed concurrently by multiple preemptible tasks on the same CPU.  The original code assumes bq_enqueue() and __dev_flush() run atomically with respect to each other on the same CPU, relying on local_bh_disable() to prevent preemption. However, on PREEMPT_RT, local_bh_disable() only calls migrate_disable() (when PREEMPT_RT_NEEDS_BH_LOCK is not set) and does not disable preemption, which allows CFS scheduling to preempt a task during bq_xmit_all(), enabling another task on the same CPU to enter bq_enqueue() and operate on the same per-CPU bq concurrently.  This leads to several races:  1. Double-free / use-after-free on bq-\u003Eq[]: bq_xmit_all() snapshots    cnt = bq-\u003Ecount, then iterates bq-\u003Eq[0..cnt-1] to transmit frames.    If preempted after the snapshot, a second task can call bq_enqueue()    -\u003E bq_xmit_all() on the same bq, transmitting (and freeing) the    same frames. When the first task resumes, it operates on stale    pointers in bq-\u003Eq[], causing use-after-free.  2. bq-\u003Ecount and bq-\u003Eq[] corruption: concurrent bq_enqueue() modifying    bq-\u003Ecount and bq-\u003Eq[] while bq_xmit_all() is reading them.  3. dev_rx/xdp_prog teardown race: __dev_flush() clears bq-\u003Edev_rx and    bq-\u003Exdp_prog after bq_xmit_all(). If preempted between    bq_xmit_all() return and bq-\u003Edev_rx = NULL, a preempting    bq_enqueue() sees dev_rx still set (non-NULL), skips adding bq to    the flush_list, and enqueues a frame. When __dev_flush() resumes,    it clears dev_rx and removes bq from the flush_list, orphaning the    newly enqueued frame.  4. __list_del_clearprev() on flush_node: similar to the cpumap race,    both tasks can call __list_del_clearprev() on the same flush_node,    the second dereferences the prev pointer already set to NULL.  The race between task A (__dev_flush -\u003E bq_xmit_all) and task B (bq_enqueue -\u003E bq_xmit_all) on the same CPU:    Task A (xdp_do_flush)          Task B (ndo_xdp_xmit redirect)   ----------------------         --------------------------------   __dev_flush(flush_list)     bq_xmit_all(bq)       cnt = bq-\u003Ecount  /* e.g. 16 */       /* start iterating bq-\u003Eq[] */     \u003C-- CFS preempts Task A --\u003E                                    bq_enqueue(dev, xdpf)                                      bq-\u003Ecount == DEV_MAP_BULK_SIZE                                      bq_xmit_all(bq, 0)                                        cnt = bq-\u003Ecount  /* same 16! */                                        ndo_xdp_xmit(bq-\u003Eq[])                                        /* frames freed by driver */                                        bq-\u003Ecount = 0     \u003C-- Task A resumes --\u003E       ndo_xdp_xmit(bq-\u003Eq[])       /* use-after-free: frames already freed! */  Fix this by adding a local_lock_t to xdp_dev_bulk_queue and acquiring it in bq_enqueue() and __dev_flush(). These paths already run under local_bh_disable(), so use local_lock_nested_bh() which on non-RT is a pure annotation with no overhead, and on PREEMPT_RT provides a per-CPU sleeping lock that serializes access to the bq.",
  "published": "2026-03-25T11:16:24Z",
  "severity": "high",
  "cvss": 7,
  "cvssVector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
  "epss": 0.00094,
  "epssPercentile": 0.00565,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
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      "product": "bpftool6.18",
      "release": "amzn 2023",
      "fixedVersion": "1:6.18.20-20.229.amzn2023",
      "fix": "ALAS2023-2026-1596",
      "url": "https://patchblox.com/security/fix/linux/alas2023-2026-1596",
      "released": "2026-04-27T09:00:00Z"
    },
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      "fix": "ALAS2023-2026-1596",
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    },
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      "fix": "ALAS2023-2026-1596",
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      "released": "2026-04-27T09:00:00Z"
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      "fix": "ALAS2023-2026-1596",
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      "fix": "ALAS2023-2026-1596",
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    },
    {
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      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-23294",
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    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T13:06:02Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}