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

  - net: switchdev: Convert blocking notification chain to a raw one A blocking notification chain uses a     read-write semaphore to protect the integrity of the chain. The semaphore is acquired for writing when     adding / removing notifiers to / from the chain and acquired for reading when traversing the chain and     informing notifiers about an event. In case of the blocking switchdev notification chain, recursive     notifications are possible which leads to the semaphore being acquired twice for reading and to lockdep     warnings being generated [1]. Specifically, this can happen when the bridge driver processes a     SWITCHDEV_BRPORT_UNOFFLOADED event which causes it to emit notifications about deferred events when     calling switchdev_deferred_process(). Fix this by converting the notification chain to a raw notification     chain in a similar fashion to the netdev notification chain. Protect the chain using the RTNL mutex by     acquiring it when modifying the chain. Events are always informed under the RTNL mutex, but add an     assertion in call_switchdev_blocking_notifiers() to make sure this is not violated in the future. Maintain     the blocking prefix as events are always emitted from process context and listeners are allowed to     block. [1]: WARNING: possible recursive locking detected 6.14.0-rc4-custom-g079270089484 #1 Not tainted
    -------------------------------------------- ip/52731 is trying to acquire lock: ffffffff850918d8     ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0 but task     is already holding lock: ffffffff850918d8 ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at:
    blocking_notifier_call_chain+0x58/0xa0 other info that might help us debug this: Possible unsafe locking     scenario: CPU0 ---- lock((switchdev_blocking_notif_chain).rwsem);
    lock((switchdev_blocking_notif_chain).rwsem); *** DEADLOCK *** May be due to missing lock nesting notation     3 locks held by ip/52731: #0: ffffffff84f795b0 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x727/0x1dc0 #1:
    ffffffff8731f628 (&net->rtnl_mutex){+.+.}-{4:4}, at: rtnl_newlink+0x790/0x1dc0 #2: ffffffff850918d8     ((switchdev_blocking_notif_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x58/0xa0 stack     backtrace: ... ? __pfx_down_read+0x10/0x10 ? __pfx_mark_lock+0x10/0x10 ?
    __pfx_switchdev_port_attr_set_deferred+0x10/0x10 blocking_notifier_call_chain+0x58/0xa0     switchdev_port_attr_notify.constprop.0+0xb3/0x1b0 ? __pfx_switchdev_port_attr_notify.constprop.0+0x10/0x10     ? mark_held_locks+0x94/0xe0 ? switchdev_deferred_process+0x11a/0x340     switchdev_port_attr_set_deferred+0x27/0xd0 switchdev_deferred_process+0x164/0x340     br_switchdev_port_unoffload+0xc8/0x100 [bridge] br_switchdev_blocking_event+0x29f/0x580 [bridge]     notifier_call_chain+0xa2/0x440 blocking_notifier_call_chain+0x6e/0xa0     switchdev_bridge_port_unoffload+0xde/0x1a0 ... (CVE-2025-21986)

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Linux Distros Unpatched Vulnerability : CVE-2025-21986

medium Nessus Plugin ID 244890

Version 1.2

Version 1.1

Version 1.2 Sep 1, 2025, 12:37 PM CVSS metrics ("Cvssv4 score" set to 0.0) CVSSv2 severity (based on None, severity decreased from "High" to "Low") Detection (updated detection logic) Plugin metadata Plugin Feed: 202509011237
Version 1.1 Aug 7, 2025, 6:51 PM New Plugin Feed: 202508071851