CVE-2026-64378

HIGHPre-NVD 7.87.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 7.8 from GitHub Security Advisory (severity: HIGH) published 2026-07-25. A secondary CVSS source baseline 7.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week
7.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 7.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
7.8
EG Score
7.8HIGHmedium confidence
EG Risk
35
EG Risk 35/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity78% × 45%
Impact severity (EG Severity): CVSS 7.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.1% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
below the 1st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.8): severity, escalated by confirmed exploitation. This CVE's 7.8 is its impact severity (EG Severity), not escalated.

EG Severity
7.8 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-19). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

July 25, 2026

Last Modified

October 19, 2026

Advisory Details (7)

Auto-updated Jul 27, 2026
Patch available.
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/cba38ec4cbd3a7b8b942a8d52531a05be8a9ff0d
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/c923cc3cb5cd8945ceaf08252754110643446593
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/685fc15a410885b6d4dee64de0dce721b9428b12
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/5c3265f3252b2ee50707adaaa3f9bd0df3df72de
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/53eeaf4d63068dbc7708b0c7adb20151c812feca
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/3c9c9648f77e4d14e50676bc51c2174ba9c8d361
Web page

writeback: fix race between cgroup_writeback_umount() and inode_switch_wbs() - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/087d5b8b501c570f84bf655164e6698c3ce146e0

Vendor Advisories for CVE-2026-64378(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(14)

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(6 across 4 ecosystems)
Debian:11(2)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 5.10.92-2 (55 versions)
  • every version up to 5.10.262-1: fixed in 5.10.262-1
—
linux-6.16.1.106-3~deb11u1 ... 6.1.177-1~deb11u1 (22 versions)
  • every version up to 6.1.180-1~deb11u1: fixed in 6.1.180-1~deb11u1
—
Debian:12(2)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 6.1.99-1 (55 versions)
  • every version up to 6.1.180-1: fixed in 6.1.180-1
—
linux-6.12—
  • every version up to 6.12.100-1~deb12u1: fixed in 6.12.100-1~deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.38-1 ... 6.12.95-1~bpo12+1 (30 versions)
  • every version up to 6.12.96-1: fixed in 6.12.96-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.12.100-1 ... 7.1~rc7-1~exp1 (159 versions)
  • every version up to 7.1.4-1: fixed in 7.1.4-1
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(14)

Data Freshness Timeline

(refreshed 22× in last 7d / 70× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 329 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 229 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-19 21:41 UTCEG score recompute
  2. 2026-10-19 21:41 UTCVendor advisory
  3. 2026-10-19 21:40 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  4. 2026-10-19 20:45 UTCEG score recompute
  5. 2026-10-19 20:45 UTCVendor advisory
  6. 2026-10-19 20:44 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  7. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  8. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  9. 2026-10-18 03:22 UTCEG score recompute
  10. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  11. 2026-10-16 17:14 UTCEG score recompute
  12. 2026-10-16 17:14 UTCVendor advisory
  13. 2026-10-16 17:14 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  14. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  15. 2026-10-16 15:51 UTCEG score recompute
  16. 2026-10-16 15:51 UTCVendor advisory
  17. 2026-10-16 15:51 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  18. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  19. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  20. 2026-10-13 11:41 UTCEG score recompute
  21. 2026-10-13 11:41 UTCVendor advisory
  22. 2026-10-13 11:41 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  24. 2026-10-12 15:48 UTCEG score recompute
  25. 2026-10-11 19:32 UTCEG score recompute
Show 75 more
  1. 2026-10-11 16:47 UTCEG score recompute
  2. 2026-10-11 14:09 UTCEG score recompute
  3. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  6. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  7. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  8. 2026-10-07 04:35 UTCEG score recompute
  9. 2026-10-07 04:35 UTCVendor advisory
  10. 2026-10-07 04:35 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  11. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  12. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  13. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  14. 2026-10-04 07:32 UTCVendor advisory
  15. 2026-10-04 07:32 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  16. 2026-10-02 19:24 UTCEG score recompute
  17. 2026-10-02 19:24 UTCVendor advisory
  18. 2026-10-02 19:24 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  19. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  20. 2026-10-01 15:45 UTCVendor advisory
  21. 2026-10-01 15:45 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  22. 2026-10-01 04:15 UTCEG score recompute
  23. 2026-10-01 04:15 UTCVendor advisory
  24. 2026-10-01 04:14 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  25. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  26. 2026-09-29 08:30 UTCEG score recompute
  27. 2026-09-29 08:30 UTCVendor advisory
  28. 2026-09-29 08:29 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  29. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  30. 2026-09-28 04:13 UTCEG score recompute
  31. 2026-09-28 04:13 UTCVendor advisory
  32. 2026-09-28 04:13 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  33. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  34. 2026-09-25 09:42 UTCEG score recompute
  35. 2026-09-25 09:42 UTCVendor advisory
  36. 2026-09-25 09:42 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  37. 2026-09-24 09:23 UTCVendor advisory
  38. 2026-09-24 09:23 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  39. 2026-09-23 22:09 UTCVendor advisory
  40. 2026-09-23 22:09 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  41. 2026-09-23 09:16 UTCVendor advisory
  42. 2026-09-23 09:16 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  43. 2026-09-22 22:02 UTCEG score recompute
  44. 2026-09-22 22:02 UTCVendor advisory
  45. 2026-09-22 22:01 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  46. 2026-09-20 01:25 UTCEG score recompute
  47. 2026-09-20 01:25 UTCVendor advisory
  48. 2026-09-20 01:25 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  49. 2026-09-18 19:47 UTCEG score recompute
  50. 2026-09-18 19:47 UTCVendor advisory
  51. 2026-09-18 19:47 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  52. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  53. 2026-09-18 02:47 UTCEG score recompute
  54. 2026-09-18 02:47 UTCVendor advisory
  55. 2026-09-18 02:47 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  56. 2026-09-17 01:54 UTCEG score recompute
  57. 2026-09-17 01:54 UTCVendor advisory
  58. 2026-09-17 01:54 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  59. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  60. 2026-09-16 06:30 UTCEG score recompute
  61. 2026-09-16 06:30 UTCVendor advisory
  62. 2026-09-16 06:30 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  63. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · below the 1st percentile
  64. 2026-09-15 09:24 UTCEG score recompute
  65. 2026-09-15 09:24 UTCVendor advisory
  66. 2026-09-15 09:24 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  67. 2026-09-14 11:48 UTCVendor advisory
  68. 2026-09-14 11:48 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  69. 2026-09-14 00:33 UTCEG score recompute
  70. 2026-09-14 00:33 UTCVendor advisory
  71. 2026-09-14 00:33 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  72. 2026-09-13 13:19 UTCVendor advisory
  73. 2026-09-13 13:19 UTCGHSA enrichmentGHSA-325c-m2q7-75hg · GitHub severity HIGH · GitHub CVSS 7.8
  74. 2026-09-13 02:05 UTCEG score recompute
  75. 2026-09-13 02:05 UTCVendor advisory

Frequently asked(5)

What is CVE-2026-64378?
CVE-2026-64378 is a high-severity vulnerability; its CVE record was published on July 25, 2026. In the Linux kernel, the following vulnerability has been resolved: writeback: fix race between cgroupwritebackumount() and inodeswitchwbs() When a container exits, the following BUG_ON() is occasionally triggered: ================================================================== VFS: Busy inodes…
When was the CVE record for CVE-2026-64378 published?
The CVE record for CVE-2026-64378 was published on July 25, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 19, 2026; the record at its source may have been updated since.
Is CVE-2026-64378 actively exploited?
CVE-2026-64378 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (below the 1st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-64378?
CVE-2026-64378 has a CVSS base score of 7.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-64378?
A fix for CVE-2026-64378 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-64378 are linked in the Vendor Advisories panel on this page.

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