Vulnerability-Lookup

GHSA-7G8G-MVQ9-46W7

Vulnerability from github – Published: 2026-02-14 18:30 – Updated: 2026-03-19 18:31

Details

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

linkwatch: use __dev_put() in callers to prevent UAF

After linkwatch_do_dev() calls __dev_put() to release the linkwatch reference, the device refcount may drop to 1. At this point, netdev_run_todo() can proceed (since linkwatch_sync_dev() sees an empty list and returns without blocking), wait for the refcount to become 1 via netdev_wait_allrefs_any(), and then free the device via kobject_put().

This creates a use-after-free when __linkwatch_run_queue() tries to call netdev_unlock_ops() on the already-freed device.

Note that adding netdev_lock_ops()/netdev_unlock_ops() pair in netdev_run_todo() before kobject_put() would not work, because netdev_lock_ops() is conditional - it only locks when netdev_need_ops_lock() returns true. If the device doesn't require ops_lock, linkwatch won't hold any lock, and netdev_run_todo() acquiring the lock won't provide synchronization.

Fix this by moving __dev_put() from linkwatch_do_dev() to its callers. The device reference logically pairs with de-listing the device, so it's reasonable for the caller that did the de-listing to release it. This allows placing __dev_put() after all device accesses are complete, preventing UAF.

The bug can be reproduced by adding mdelay(2000) after linkwatch_do_dev() in __linkwatch_run_queue(), then running:

ip tuntap add mode tun name tun_test ip link set tun_test up ip link set tun_test carrier off ip link set tun_test carrier on sleep 0.5 ip tuntap del mode tun name tun_test

KASAN report:

================================================================== BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline] BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123

CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events_unbound linkwatch_event Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595 netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] netdev_unlock_ops include/net/netdev_lock.h:47 [inline] __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3421 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 ==================================================================

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-23192"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-02-14T17:15:57Z",
    "severity": "HIGH"
  },
  "details": "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\u0027t require\nops_lock, linkwatch won\u0027t hold any lock, and netdev_run_todo()\nacquiring the lock won\u0027t 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\u0027s 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 ==================================================================",
  "id": "GHSA-7g8g-mvq9-46w7",
  "modified": "2026-03-19T18:31:14Z",
  "published": "2026-02-14T18:30:16Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23192"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/83b67cc9be9223183caf91826d9c194d7fb128fa"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-23192 (GCVE-0-2026-23192)

Vulnerability from cvelistv5 – Published: 2026-02-14 16:27 – Updated: 2026-08-05 12:20

Title

linkwatch: use __dev_put() in callers to prevent UAF

Summary

In the Linux kernel, the following vulnerability has been resolved: linkwatch: use __dev_put() in callers to prevent UAF After linkwatch_do_dev() calls __dev_put() to release the linkwatch reference, the device refcount may drop to 1. At this point, netdev_run_todo() can proceed (since linkwatch_sync_dev() sees an empty list and returns without blocking), wait for the refcount to become 1 via netdev_wait_allrefs_any(), and then free the device via kobject_put(). This creates a use-after-free when __linkwatch_run_queue() tries to call netdev_unlock_ops() on the already-freed device. Note that adding netdev_lock_ops()/netdev_unlock_ops() pair in netdev_run_todo() before kobject_put() would not work, because netdev_lock_ops() is conditional - it only locks when netdev_need_ops_lock() returns true. If the device doesn't require ops_lock, linkwatch won't hold any lock, and netdev_run_todo() acquiring the lock won't provide synchronization. Fix this by moving __dev_put() from linkwatch_do_dev() to its callers. The device reference logically pairs with de-listing the device, so it's reasonable for the caller that did the de-listing to release it. This allows placing __dev_put() after all device accesses are complete, preventing UAF. The bug can be reproduced by adding mdelay(2000) after linkwatch_do_dev() in __linkwatch_run_queue(), then running: ip tuntap add mode tun name tun_test ip link set tun_test up ip link set tun_test carrier off ip link set tun_test carrier on sleep 0.5 ip tuntap del mode tun name tun_test KASAN report: ================================================================== BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline] BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123 CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events_unbound linkwatch_event Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595 netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] netdev_unlock_ops include/net/netdev_lock.h:47 [inline] __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3421 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 </TASK> ==================================================================

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root Scorecard

References

2 references

URL	Tags
https://git.kernel.org/stable/c/2718ae6af7445ba2e…
https://git.kernel.org/stable/c/83b67cc9be9223183…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 04efcee6ef8d0f01eef495db047e7216d6e6e38f , < 2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb (git) Affected: 04efcee6ef8d0f01eef495db047e7216d6e6e38f , < 83b67cc9be9223183caf91826d9c194d7fb128fa (git)
Linux	Linux	Affected: 6.15 Unaffected: 0 , < 6.15 (semver) Unaffected: 6.18.10 , ≤ 6.18.* (semver) Unaffected: 6.19 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/link_watch.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb",
              "status": "affected",
              "version": "04efcee6ef8d0f01eef495db047e7216d6e6e38f",
              "versionType": "git"
            },
            {
              "lessThan": "83b67cc9be9223183caf91826d9c194d7fb128fa",
              "status": "affected",
              "version": "04efcee6ef8d0f01eef495db047e7216d6e6e38f",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/link_watch.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.10",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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\u0027t require\nops_lock, linkwatch won\u0027t hold any lock, and netdev_run_todo()\nacquiring the lock won\u0027t 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\u0027s 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 =================================================================="
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is triggered through local operations: creating a tun device, manipulating carrier state via netlink (RTM_SETLINK/IFLA_CARRIER), and deleting the device. All require local system access via syscalls/netlink.\nAC:L - The attacker controls both sides of the race - they fire the linkwatch event by changing carrier state AND initiate device deletion. The reproducer shows reliable triggering with a simple sleep. The attacker creates and controls the race condition.\nPR:L - Creating tun devices and manipulating carrier state requires CAP_NET_ADMIN, but this capability is available in user namespaces via unshare -Urn (ns_capable check in tun.c:2757), making this reachable by unprivileged local users.\nUI:N - No user interaction is needed. The attacker autonomously creates the device, manipulates carrier state, and triggers the race to cause the UAF.\nS:U - The vulnerability results in kernel memory corruption within the same security authority (the kernel). There is no crossing of a virtualization or sandbox boundary.\nC:H - This is a use-after-free on a net_device structure. The freed memory can be reclaimed and filled with attacker-controlled data via heap spraying, enabling arbitrary kernel memory reads through the stale pointer.\nI:H - The UAF on the net_device structure allows heap spraying to place attacker-controlled data in the freed allocation. This enables write primitives and potential control flow hijacking through the stale device pointer operations.\nA:H - The UAF reliably causes a kernel crash/oops as demonstrated by the KASAN report. Accessing freed memory in netdev_unlock_ops triggers an immediate kernel crash."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:20:34.811Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb"
        },
        {
          "url": "https://git.kernel.org/stable/c/83b67cc9be9223183caf91826d9c194d7fb128fa"
        }
      ],
      "title": "linkwatch: use __dev_put() in callers to prevent UAF",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23192",
    "datePublished": "2026-02-14T16:27:19.557Z",
    "dateReserved": "2026-01-13T15:37:45.985Z",
    "dateUpdated": "2026-08-05T12:20:34.811Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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GHSA-7G8G-MVQ9-46W7

CVE-2026-23192 (GCVE-0-2026-23192)

Tags

Sightings

Nomenclature

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