In the Linux kernel, the following vulnerability has been resolved: net: qrtr: Fix a refcount bug in qrtr_recvmsg() Syzbot reported a bug as following: refcount_t: addition on 0; use-after-free. ... RIP: 0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25 ... Call Trace: <TASK> __refcount_add include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] qrtr_node_acquire net/qrtr/af_qrtr.c:202 [inline] qrtr_node_lookup net/qrtr/af_qrtr.c:398 [inline] qrtr_send_resume_tx net/qrtr/af_qrtr.c:1003 [inline] qrtr_recvmsg+0x85f/0x990 net/qrtr/af_qrtr.c:1070 sock_recvmsg_nosec net/socket.c:1017 [inline] sock_recvmsg+0xe2/0x160 net/socket.c:1038 qrtr_ns_worker+0x170/0x1700 net/qrtr/ns.c:688 process_one_work+0x991/0x15c0 kernel/workqueue.c:2390 worker_thread+0x669/0x1090 kernel/workqueue.c:2537 It occurs in the concurrent scenario of qrtr_recvmsg() and qrtr_endpoint_unregister() as following: cpu0 cpu1 qrtr_recvmsg qrtr_endpoint_unregister qrtr_send_resume_tx qrtr_node_release qrtr_node_lookup mutex_lock(&qrtr_node_lock) spin_lock_irqsave(&qrtr_nodes_lock, ) refcount_dec_and_test(&node->ref) [node->ref == 0] radix_tree_lookup [node != NULL] __qrtr_node_release qrtr_node_acquire spin_lock_irqsave(&qrtr_nodes_lock, ) kref_get(&node->ref) [WARNING] ... mutex_unlock(&qrtr_node_lock) Use qrtr_node_lock to protect qrtr_node_lookup() implementation, this is actually improving the protection of node reference.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-005660 advisory.

    In the Linux kernel, the following vulnerability has been resolved:

    net: qrtr: Fix a refcount bug in qrtr_recvmsg()

    Syzbot reported a bug as following:

    refcount_t: addition on 0; use-after-free.
    ...
    RIP: 0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25     ...
    Call Trace:
     <TASK>
     __refcount_add include/linux/refcount.h:199 [inline]
     __refcount_inc include/linux/refcount.h:250 [inline]      refcount_inc include/linux/refcount.h:267 [inline]      kref_get include/linux/kref.h:45 [inline]      qrtr_node_acquire net/qrtr/af_qrtr.c:202 [inline]      qrtr_node_lookup net/qrtr/af_qrtr.c:398 [inline]      qrtr_send_resume_tx net/qrtr/af_qrtr.c:1003 [inline]      qrtr_recvmsg+0x85f/0x990 net/qrtr/af_qrtr.c:1070      sock_recvmsg_nosec net/socket.c:1017 [inline]      sock_recvmsg+0xe2/0x160 net/socket.c:1038      qrtr_ns_worker+0x170/0x1700 net/qrtr/ns.c:688      process_one_work+0x991/0x15c0 kernel/workqueue.c:2390      worker_thread+0x669/0x1090 kernel/workqueue.c:2537

    It occurs in the concurrent scenario of qrtr_recvmsg() and     qrtr_endpoint_unregister() as following:

            cpu0                                    cpu1     qrtr_recvmsg                            qrtr_endpoint_unregister     qrtr_send_resume_tx                     qrtr_node_release     qrtr_node_lookup                        mutex_lock(&qrtr_node_lock)     spin_lock_irqsave(&qrtr_nodes_lock, )   refcount_dec_and_test(&node->ref) [node->ref == 0]     radix_tree_lookup [node != NULL]        __qrtr_node_release     qrtr_node_acquire                       spin_lock_irqsave(&qrtr_nodes_lock, )     kref_get(&node->ref) [WARNING]          ...
                                            mutex_unlock(&qrtr_node_lock)

    Use qrtr_node_lock to protect qrtr_node_lookup() implementation, this     is actually improving the protection of node reference.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - In the Linux kernel, the following vulnerability has been resolved: net: qrtr: Fix a refcount bug in     qrtr_recvmsg() Syzbot reported a bug as following: refcount_t: addition on 0; use-after-free. ... RIP:
    0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25 ... Call Trace: <TASK> __refcount_add     include/linux/refcount.h:199 [inline] __refcount_inc include/linux/refcount.h:250 [inline] refcount_inc     include/linux/refcount.h:267 [inline] kref_get include/linux/kref.h:45 [inline] qrtr_node_acquire     net/qrtr/af_qrtr.c:202 [inline] qrtr_node_lookup net/qrtr/af_qrtr.c:398 [inline] qrtr_send_resume_tx     net/qrtr/af_qrtr.c:1003 [inline] qrtr_recvmsg+0x85f/0x990 net/qrtr/af_qrtr.c:1070 sock_recvmsg_nosec     net/socket.c:1017 [inline] sock_recvmsg+0xe2/0x160 net/socket.c:1038 qrtr_ns_worker+0x170/0x1700     net/qrtr/ns.c:688 process_one_work+0x991/0x15c0 kernel/workqueue.c:2390 worker_thread+0x669/0x1090     kernel/workqueue.c:2537 It occurs in the concurrent scenario of qrtr_recvmsg() and     qrtr_endpoint_unregister() as following: cpu0 cpu1 qrtr_recvmsg qrtr_endpoint_unregister     qrtr_send_resume_tx qrtr_node_release qrtr_node_lookup mutex_lock(&qrtr_node_lock)     spin_lock_irqsave(&qrtr_nodes_lock, ) refcount_dec_and_test(&node->ref) [node->ref == 0] radix_tree_lookup     [node != NULL] __qrtr_node_release qrtr_node_acquire spin_lock_irqsave(&qrtr_nodes_lock, )     kref_get(&node->ref) [WARNING] ... mutex_unlock(&qrtr_node_lock) Use qrtr_node_lock to protect     qrtr_node_lookup() implementation, this is actually improving the protection of node reference.
    (CVE-2023-53445)

Note that Nessus relies on the presence of the package as reported by the vendor.

An update of the linux package has been released.

ID	Name	Product	Family	Severity
300884	Unity Linux 20.1070a Security Update: kernel (UTSA-2026-005660)	Nessus	Unity Linux Local Security Checks	medium
265507	Linux Distros Unpatched Vulnerability : CVE-2023-53445	Nessus	Misc.	medium
151965	Photon OS 4.0: Linux PHSA-2021-4.0-0065	Nessus	PhotonOS Local Security Checks	high

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