{"apiVersion":"1.0","identifier":"CVE-2026-74543","description":"In the Linux kernel, the following vulnerability has been resolved: net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister() syzbot reported a memory leak [1] in the UDP tunnel NIC offload code. When device registration fails (e.g. in register_netdevice()), netdev core unwinds by sending a single NETDEV_UNREGISTER notification. If work was queued during NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister() returns early: if (utn->work_pending) return; Because failed registrations do not enter netdev_wait_allrefs_any(), no subsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the struct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked permanently. Fix this by removing the early return. Instead, synchronously cancel any pending work with cancel_delayed_work_sync() before freeing @utn. To be able to call cancel_delayed_work_sync() while holding RTNL (the work also needs RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL is contended, requeue the work with a 1 jiffy delay (via queue_delayed_work()) to prevent high CPU contention while waiting for RTNL lock. The utn->work_pending bookkeeping is no longer needed and is removed, as the workqueue core already tracks the pending/running state of the work. [1] BUG: memory leak unreferenced object 0xffff888127d5f840 (size 96): comm -syz-executor-, pid 5806, jiffies 4294942188 backtrace (crc 99fdb6c8): __kmalloc_noprof+0x3bf/0x550 udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline] udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline] udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931 notifier_call_chain+0x59/0x160 kernel/notifier.c:85 call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250 register_netdevice+0xc10/0xeb0 net/core/dev.c:11478","publishedAt":"2026-08-15T13:17:59","lastModifiedAt":"2026-08-17T06:19:51","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-74543","cvssScore":null,"cvssVector":"Pending","epssProbability":0.00168,"riskScore":0,"affectedProduct":"Linux kernel","affectedVersions":"unknown","vulnerabilityType":"Kernel","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-74543","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-74543","en":"https://www.redsauce.net/en/cves/CVE-2026-74543","fr":"https://www.redsauce.net/fr/cves/CVE-2026-74543","pt":"https://www.redsauce.net/pt/cves/CVE-2026-74543","de":"https://www.redsauce.net/de/cves/CVE-2026-74543","sk":"https://www.redsauce.net/sk/cves/CVE-2026-74543","el":"https://www.redsauce.net/el/cves/CVE-2026-74543"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-74543"}}