# cveboard — Historical CVE brief

## Instructions for the operator's AI
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Fix information unknown; no fixed version is derived here. Missing information does not prove that no fix exists.
Exploitation unknown; this catalogue does not assess exploitation.

## Source facts (JSON-quoted data)
CNA source text (English)
id: "CVE-2026-23192"
idYear: 2026
status: "PUBLISHED"
publishedAt: "2026-02-14T16:27:19.557Z"
updatedAt: "2026-08-05T12:20:34.811Z"
importedAt: "2026-10-24T01:58:02.025Z"
snapshot: {"id":"cve_2026-10-24_midnight_baseline","at":"2026-10-24T00:00:00.000Z","source":"https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"}
url: "https://cveboard.org/cve/CVE-2026-23192"
json: "https://cveboard.org/cve/CVE-2026-23192.json"
sourceURL: "https://www.cve.org/CVERecord?id=CVE-2026-23192"
title: "linkwatch: use __dev_put() in callers to prevent UAF"
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nlinkwatch: use __dev_put() in callers to prevent UAF\n\nAfter linkwatch_do_dev() calls __dev_put() to release the linkwatch\nreference, the device refcount may drop to 1. At this point,\nnetdev_run_todo() can proceed (since linkwatch_sync_dev() sees an\nempty list and returns without blocking), wait for the refcount to\nbecome 1 via netdev_wait_allrefs_any(), and then free the device\nvia kobject_put().\n\nThis creates a use-after-free when __linkwatch_run_queue() tries to\ncall netdev_unlock_ops() on the already-freed device.\n\nNote that adding netdev_lock_ops()/netdev_unlock_ops() pair in\nnetdev_run_todo() before kobject_put() would not work, because\nnetdev_lock_ops() is conditional - it only locks when\nnetdev_need_ops_lock() returns true. If the device doesn't require\nops_lock, linkwatch won't hold any lock, and netdev_run_todo()\nacquiring the lock won't provide synchronization.\n\nFix this by moving __dev_put() from linkwatch_do_dev() to its\ncallers. The device reference logically pairs with de-listing the\ndevice, so it's reasonable for the caller that did the de-listing\nto release it. This allows placing __dev_put() after all device\naccesses are complete, preventing UAF.\n\nThe bug can be reproduced by adding mdelay(2000) after\nlinkwatch_do_dev() in __linkwatch_run_queue(), then running:\n\n  ip tuntap add mode tun name tun_test\n  ip link set tun_test up\n  ip link set tun_test carrier off\n  ip link set tun_test carrier on\n  sleep 0.5\n  ip tuntap del mode tun name tun_test\n\nKASAN report:\n\n ==================================================================\n BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123\n\n CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n Workqueue: events_unbound linkwatch_event\n Call Trace:\n  \u003cTASK\u003e\n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\n  print_address_description mm/kasan/report.c:378 [inline]\n  print_report+0x156/0x4c9 mm/kasan/report.c:482\n  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595\n  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304\n  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257\n  process_scheduled_works kernel/workqueue.c:3340 [inline]\n  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421\n  kthread+0x3b3/0x730 kernel/kthread.c:463\n  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n  \u003c/TASK\u003e\n =================================================================="
affected: [{"versions":[{"version":"04efcee6ef8d0f01eef495db047e7216d6e6e38f","status":"affected","versionType":"git","lessThan":"2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb"},{"version":"04efcee6ef8d0f01eef495db047e7216d6e6e38f","status":"affected","versionType":"git","lessThan":"83b67cc9be9223183caf91826d9c194d7fb128fa"}],"vendor":"Linux","product":"Linux","defaultStatus":"unaffected"},{"versions":[{"version":"6.15","status":"affected"},{"version":"0","status":"unaffected","versionType":"semver","lessThan":"6.15"},{"version":"6.18.10","status":"unaffected","versionType":"semver","lessThanOrEqual":"6.18.*"},{"version":"6.19","status":"unaffected","versionType":"original_commit_for_fix","lessThanOrEqual":"*"}],"vendor":"Linux","product":"Linux","defaultStatus":"affected"}]

## Source licences and attribution
CISA Known Exploited Vulnerabilities: https://www.cisa.gov/known-exploited-vulnerabilities-catalog (US government work)
GitHub Advisory Database: https://github.com/advisories (CC BY 4.0)
Have I Been Pwned: https://haveibeenpwned.com/ (CC BY 4.0)
CVE Program (CVE records): https://www.cve.org/Legal/TermsOfUse (CVE Terms of Use)
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