Vulnerability-Lookup

FKIE_CVE-2026-64378

Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-10-19 21:17

Severity

7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() When a container exits, the following BUG_ON() is occasionally triggered: ================================================================== VFS: Busy inodes after unmount of sdb (ext4) ------------[ cut here ]------------ kernel BUG at fs/super.c:695! CPU: 3 PID: 6 Comm: containerd-shim Tainted: G OE K 6.6 #1 pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : generic_shutdown_super+0xf0/0x100 lr : generic_shutdown_super+0xf0/0x100 Call trace: generic_shutdown_super+0xf0/0x100 kill_block_super+0x20/0x48 ext4_kill_sb+0x28/0x60 deactivate_locked_super+0x54/0x130 deactivate_super+0x84/0xa0 cleanup_mnt+0xa4/0x140 __cleanup_mnt+0x18/0x28 task_work_run+0x78/0xe0 do_notify_resume+0x204/0x240 ================================================================== The root cause is a race between cgroup_writeback_umount() and inode_switch_wbs()/cleanup_offline_cgwb(). There is a window between inode_prepare_wbs_switch() returning true and the subsequent wb_queue_isw() call. Following is the process that triggers the issue: CPU A (umount) | CPU B (writeback) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ inode_switch_wbs/cleanup_offline_cgwb atomic_inc(&isw_nr_in_flight) inode_prepare_wbs_switch -> passes SB_ACTIVE check __iget(inode) generic_shutdown_super sb->s_flags &= ~SB_ACTIVE cgroup_writeback_umount(sb) smp_mb() atomic_read(&isw_nr_in_flight) rcu_barrier() -> no pending RCU callbacks flush_workqueue(isw_wq) -> nothing queued, returns evict_inodes(sb) -> Inode skipped as isw still holds a ref. sop->put_super(sb) /* destroys percpu counters */ -> VFS: Busy inodes after unmount! wb_queue_isw() queue_work(isw_wq, ...) /* later in work function */ inode_switch_wbs_work_fn process_inode_switch_wbs iput() -> evict percpu_counter_dec() // UAF! Fix this by extending the RCU read-side critical section in inode_switch_wbs() and cleanup_offline_cgwb() to cover from inode_prepare_wbs_switch() through wb_queue_isw(). Since there is no sleep in this window, rcu_read_lock() can be used. Then add a synchronize_rcu() in cgroup_writeback_umount() before the existing rcu_barrier(), so that all in-flight switchers that have passed the SB_ACTIVE check have completed queue_work() before flush_workqueue() is called. The existing rcu_barrier() is intentionally retained so this fix can be backported unchanged to stable kernels (5.10.y, 6.6.y, ...) that still queue switches via queue_rcu_work(). It is a no-op on current mainline (since commit e1b849cfa6b6 ("writeback: Avoid contention on wb->list_lock when switching inodes")) and is removed in a follow-up patch.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/087d5b8b501c570f84bf655164e6698c3ce146e0	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/3c9c9648f77e4d14e50676bc51c2174ba9c8d361	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/53eeaf4d63068dbc7708b0c7adb20151c812feca	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/5c3265f3252b2ee50707adaaa3f9bd0df3df72de	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/685fc15a410885b6d4dee64de0dce721b9428b12	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/c923cc3cb5cd8945ceaf08252754110643446593	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d	Patch

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	4.5
linux	linux_kernel	4.5

JSON

To clipboard

{
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: fix race between cgroup_writeback_umount() and inode_switch_wbs()\n\nWhen a container exits, the following BUG_ON() is occasionally triggered:\n\n==================================================================\n VFS: Busy inodes after unmount of sdb (ext4)\n ------------[ cut here ]------------\n kernel BUG at fs/super.c:695!\n CPU: 3 PID: 6 Comm: containerd-shim Tainted: G OE K 6.6 #1\n pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)\n pc : generic_shutdown_super+0xf0/0x100\n lr : generic_shutdown_super+0xf0/0x100\n Call trace:\n  generic_shutdown_super+0xf0/0x100\n  kill_block_super+0x20/0x48\n  ext4_kill_sb+0x28/0x60\n  deactivate_locked_super+0x54/0x130\n  deactivate_super+0x84/0xa0\n  cleanup_mnt+0xa4/0x140\n  __cleanup_mnt+0x18/0x28\n  task_work_run+0x78/0xe0\n  do_notify_resume+0x204/0x240\n==================================================================\n\nThe root cause is a race between cgroup_writeback_umount() and\ninode_switch_wbs()/cleanup_offline_cgwb(). There is a window between\ninode_prepare_wbs_switch() returning true and the subsequent\nwb_queue_isw() call. Following is the process that triggers the issue:\n\n      CPU A (umount)           |          CPU B (writeback)\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n                                 inode_switch_wbs/cleanup_offline_cgwb\n                                  atomic_inc(\u0026isw_nr_in_flight)\n                                  inode_prepare_wbs_switch\n                                   -\u003e passes SB_ACTIVE check\n                                   __iget(inode)\n generic_shutdown_super\n  sb-\u003es_flags \u0026= ~SB_ACTIVE\n  cgroup_writeback_umount(sb)\n   smp_mb()\n   atomic_read(\u0026isw_nr_in_flight)\n   rcu_barrier()\n    -\u003e no pending RCU callbacks\n   flush_workqueue(isw_wq)\n    -\u003e nothing queued, returns\n  evict_inodes(sb)\n   -\u003e Inode skipped as isw still holds a ref.\n  sop-\u003eput_super(sb)\n   /* destroys percpu counters */\n  -\u003e VFS: Busy inodes after unmount!\n                                  wb_queue_isw()\n                                   queue_work(isw_wq, ...)\n                                  /* later in work function */\n                                  inode_switch_wbs_work_fn\n                                   process_inode_switch_wbs\n                                    iput() -\u003e evict\n                                     percpu_counter_dec() // UAF!\n\nFix this by extending the RCU read-side critical section in\ninode_switch_wbs() and cleanup_offline_cgwb() to cover from\ninode_prepare_wbs_switch() through wb_queue_isw().  Since there is\nno sleep in this window, rcu_read_lock() can be used.  Then add a\nsynchronize_rcu() in cgroup_writeback_umount() before the existing\nrcu_barrier(), so that all in-flight switchers that have passed the\nSB_ACTIVE check have completed queue_work() before flush_workqueue()\nis called.\n\nThe existing rcu_barrier() is intentionally retained so this fix can\nbe backported unchanged to stable kernels (5.10.y, 6.6.y, ...) that\nstill queue switches via queue_rcu_work(). It is a no-op on current\nmainline (since commit e1b849cfa6b6 (\"writeback: Avoid contention on\nwb-\u003elist_lock when switching inodes\")) and is removed in a follow-up\npatch."
    }
  ],
  "id": "CVE-2026-64378",
  "lastModified": "2026-10-19T21:17:34.017",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
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        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
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        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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          "options": [
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            {
              "technicalImpact": "total"
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          "role": "CISA Coordinator",
          "timestamp": "2026-10-16T15:39:41.597767Z",
          "version": "2.0.3"
        }
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
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          "value": "CWE-362"
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      "source": "nvd@nist.gov",
      "type": "Primary"
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          "lang": "en",
          "value": "CWE-362"
        }
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      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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}

CVE-2026-64378 (GCVE-0-2026-64378)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-10-19 20:38

Title

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs()

Summary

Severity

7.8 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-10-16 15:39 UTC

CWE

CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

7 references

URL	Tags
https://git.kernel.org/stable/c/087d5b8b501c570f8…
https://git.kernel.org/stable/c/3c9c9648f77e4d14e…
https://git.kernel.org/stable/c/5c3265f3252b2ee50…
https://git.kernel.org/stable/c/c923cc3cb5cd8945c…
https://git.kernel.org/stable/c/685fc15a410885b6d…
https://git.kernel.org/stable/c/53eeaf4d63068dbc7…
https://git.kernel.org/stable/c/cba38ec4cbd3a7b8b…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < 087d5b8b501c570f84bf655164e6698c3ce146e0 (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < 3c9c9648f77e4d14e50676bc51c2174ba9c8d361 (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < 5c3265f3252b2ee50707adaaa3f9bd0df3df72de (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < c923cc3cb5cd8945ceaf08252754110643446593 (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < 685fc15a410885b6d4dee64de0dce721b9428b12 (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < 53eeaf4d63068dbc7708b0c7adb20151c812feca (git) Affected: a1a0e23e49037c23ea84bc8cc146a03584d13577 , < cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d (git) Affected: c5cbbec54fe71c4de2d34f8c0ec8fbfdd7f17339 (git) Affected: 4.4.5 , < 4.5 (semver)
Linux	Linux	Affected: 4.5 Unaffected: 0 , < 4.5 (semver) Unaffected: 5.10.261 , ≤ 5.10.* (semver) Unaffected: 6.1.178 , ≤ 6.1.* (semver) Unaffected: 6.6.145 , ≤ 6.6.* (semver) Unaffected: 6.12.96 , ≤ 6.12.* (semver) Unaffected: 6.18.39 , ≤ 6.18.* (semver) Unaffected: 7.1.4 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-64378",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-16T15:39:41.597767Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "problemTypes": [
          {
            "descriptions": [
              {
                "cweId": "CWE-362",
                "description": "CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization (\u0027Race Condition\u0027)",
                "lang": "en",
                "type": "CWE"
              }
            ]
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-19T20:38:25.561Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fs-writeback.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "087d5b8b501c570f84bf655164e6698c3ce146e0",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "3c9c9648f77e4d14e50676bc51c2174ba9c8d361",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "5c3265f3252b2ee50707adaaa3f9bd0df3df72de",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "c923cc3cb5cd8945ceaf08252754110643446593",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "685fc15a410885b6d4dee64de0dce721b9428b12",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "53eeaf4d63068dbc7708b0c7adb20151c812feca",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "lessThan": "cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d",
              "status": "affected",
              "version": "a1a0e23e49037c23ea84bc8cc146a03584d13577",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "c5cbbec54fe71c4de2d34f8c0ec8fbfdd7f17339",
              "versionType": "git"
            },
            {
              "lessThan": "4.5",
              "status": "affected",
              "version": "4.4.5",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/fs-writeback.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.5"
            },
            {
              "lessThan": "4.5",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.178",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.145",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.39",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.4",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "4.5",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.4.5",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: fix race between cgroup_writeback_umount() and inode_switch_wbs()\n\nWhen a container exits, the following BUG_ON() is occasionally triggered:\n\n==================================================================\n VFS: Busy inodes after unmount of sdb (ext4)\n ------------[ cut here ]------------\n kernel BUG at fs/super.c:695!\n CPU: 3 PID: 6 Comm: containerd-shim Tainted: G OE K 6.6 #1\n pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)\n pc : generic_shutdown_super+0xf0/0x100\n lr : generic_shutdown_super+0xf0/0x100\n Call trace:\n  generic_shutdown_super+0xf0/0x100\n  kill_block_super+0x20/0x48\n  ext4_kill_sb+0x28/0x60\n  deactivate_locked_super+0x54/0x130\n  deactivate_super+0x84/0xa0\n  cleanup_mnt+0xa4/0x140\n  __cleanup_mnt+0x18/0x28\n  task_work_run+0x78/0xe0\n  do_notify_resume+0x204/0x240\n==================================================================\n\nThe root cause is a race between cgroup_writeback_umount() and\ninode_switch_wbs()/cleanup_offline_cgwb(). There is a window between\ninode_prepare_wbs_switch() returning true and the subsequent\nwb_queue_isw() call. Following is the process that triggers the issue:\n\n      CPU A (umount)           |          CPU B (writeback)\n~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n                                 inode_switch_wbs/cleanup_offline_cgwb\n                                  atomic_inc(\u0026isw_nr_in_flight)\n                                  inode_prepare_wbs_switch\n                                   -\u003e passes SB_ACTIVE check\n                                   __iget(inode)\n generic_shutdown_super\n  sb-\u003es_flags \u0026= ~SB_ACTIVE\n  cgroup_writeback_umount(sb)\n   smp_mb()\n   atomic_read(\u0026isw_nr_in_flight)\n   rcu_barrier()\n    -\u003e no pending RCU callbacks\n   flush_workqueue(isw_wq)\n    -\u003e nothing queued, returns\n  evict_inodes(sb)\n   -\u003e Inode skipped as isw still holds a ref.\n  sop-\u003eput_super(sb)\n   /* destroys percpu counters */\n  -\u003e VFS: Busy inodes after unmount!\n                                  wb_queue_isw()\n                                   queue_work(isw_wq, ...)\n                                  /* later in work function */\n                                  inode_switch_wbs_work_fn\n                                   process_inode_switch_wbs\n                                    iput() -\u003e evict\n                                     percpu_counter_dec() // UAF!\n\nFix this by extending the RCU read-side critical section in\ninode_switch_wbs() and cleanup_offline_cgwb() to cover from\ninode_prepare_wbs_switch() through wb_queue_isw().  Since there is\nno sleep in this window, rcu_read_lock() can be used.  Then add a\nsynchronize_rcu() in cgroup_writeback_umount() before the existing\nrcu_barrier(), so that all in-flight switchers that have passed the\nSB_ACTIVE check have completed queue_work() before flush_workqueue()\nis called.\n\nThe existing rcu_barrier() is intentionally retained so this fix can\nbe backported unchanged to stable kernels (5.10.y, 6.6.y, ...) that\nstill queue switches via queue_rcu_work(). It is a no-op on current\nmainline (since commit e1b849cfa6b6 (\"writeback: Avoid contention on\nwb-\u003elist_lock when switching inodes\")) and is removed in a follow-up\npatch."
        }
      ],
      "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 reached through local filesystem writes, cgroup teardown, and mount-namespace or filesystem unmount paths; no network protocol directly reaches the race.\nAC:L - An attacker can churn cgroup writeback switches while repeatedly triggering container or mount teardown, controlling both racing activities and amplifying the timing window.\nPR:L - A basic local or container user can dirty writable files and initiate its own cgroup or namespace teardown; lifecycle infrastructure can perform the privileged final unmount automatically.\nUI:N - The attacker can generate the writeback state and trigger teardown without requiring another user to perform an action.\nS:U - The resulting corruption affects the same host kernel security authority and does not inherently cross a VM or hardware isolation boundary.\nC:H - The delayed worker can access superblock-private state after it and its per-CPU counters have been freed, creating an exploitable use-after-free capable of exposing arbitrary kernel memory.\nI:H - The freed superblock and per-CPU counter pointers are subsequently dereferenced and modified, potentially providing attacker-influenced kernel writes and control-flow hijacking.\nA:H - The race demonstrably triggers the busy-inode BUG_ON, and configurations continuing past that check encounter a use-after-free capable of causing an oops or kernel panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:54:29.511Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/087d5b8b501c570f84bf655164e6698c3ce146e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/3c9c9648f77e4d14e50676bc51c2174ba9c8d361"
        },
        {
          "url": "https://git.kernel.org/stable/c/5c3265f3252b2ee50707adaaa3f9bd0df3df72de"
        },
        {
          "url": "https://git.kernel.org/stable/c/c923cc3cb5cd8945ceaf08252754110643446593"
        },
        {
          "url": "https://git.kernel.org/stable/c/685fc15a410885b6d4dee64de0dce721b9428b12"
        },
        {
          "url": "https://git.kernel.org/stable/c/53eeaf4d63068dbc7708b0c7adb20151c812feca"
        },
        {
          "url": "https://git.kernel.org/stable/c/cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d"
        }
      ],
      "title": "writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64378",
    "datePublished": "2026-07-25T08:50:29.006Z",
    "dateReserved": "2026-07-19T15:36:31.784Z",
    "dateUpdated": "2026-10-19T20:38:25.561Z",
    "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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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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.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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