{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.176-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.94-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.0.13-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling  A SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in send_sigio() and send_sigurg() when a process group receives a signal.  When FASYNC is configured for a process group (PIDTYPE_PGID), both functions use read_lock(\u0026tasklist_lock) to traverse the task list. However, they are frequently called from softirq context: - send_sigio() via input_inject_event -\u003e kill_fasync - send_sigurg() via tcp_check_urg -\u003e sk_send_sigurg (NET_RX_SOFTIRQ)  The deadlock is caused by the rwlock writer fairness mechanism: 1. CPU 0 (process context) holds read_lock(\u0026tasklist_lock) in do_wait(). 2. CPU 1 (process context) attempts write_lock(\u0026tasklist_lock) in    fork() or exit() and spins, which blocks all new readers. 3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception). 4. The softirq calls send_sigurg() and attempts to acquire    read_lock(\u0026tasklist_lock), deadlocking because CPU 1 is waiting.  Since PID hashing and do_each_pid_task() traversals are already RCU-protected, the read_lock on tasklist_lock is no longer strictly required for safe traversal. Fix this by replacing tasklist_lock with rcu_read_lock(), aligning the process group signaling path with the single-PID path. This also mitigates a potential remote denial of service vector via TCP URG packets.  Lockdep splat: ===================================================== WARNING: SOFTIRQ-safe -\u003e SOFTIRQ-unsafe lock order detected [...] Chain exists of:   \u0026dev-\u003eevent_lock --\u003e \u0026f_owner-\u003elock --\u003e tasklist_lock  Possible interrupt unsafe locking scenario:        CPU0                    CPU1        ----                    ----   lock(tasklist_lock);                            local_irq_disable();                            lock(\u0026dev-\u003eevent_lock);                            lock(\u0026f_owner-\u003elock);   \u003cInterrupt\u003e     lock(\u0026dev-\u003eevent_lock);  *** DEADLOCK ***",
  "id": "DEBIAN-CVE-2026-52946",
  "modified": "2026-09-09T08:47:34.609020464Z",
  "published": "2026-06-24T17:17:04.610Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-52946"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-52946"
  ]
}