CVE-2025-21634

MEDIUMNVD 5.55.5
EchelonGraph scoreMEDIUM confidence

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

Score 5.5 from GitHub Security Advisory published 2025-01-19. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2025-2583 (ENISA EUVD) · GHSA-v62x-6v8m-46vv (GitHub Security Advisories)Source: ENISA EUVD

5.5EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 5.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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

cgroup/cpuset: remove kernfs active break

A warning was found:

WARNING: CPU: 10 PID: 3486953 at fs/kernfs/file.c:828 CPU: 10 PID: 3486953 Comm: rmdir Kdump: loaded Tainted: G RIP: 0010:kernfs_should_drain_open_files+0x1a1/0x1b0 RSP: 0018:ffff8881107ef9e0 EFLAGS: 00010202 RAX: 0000000080000002 RBX: ffff888154738c00 RCX: dffffc0000000000 RDX: 0000000000000007 RSI: 0000000000000004 RDI: ffff888154738c04 RBP: ffff888154738c04 R08: ffffffffaf27fa15 R09: ffffed102a8e7180 R10: ffff888154738c07 R11: 0000000000000000 R12: ffff888154738c08 R13: ffff888750f8c000 R14: ffff888750f8c0e8 R15: ffff888154738ca0 FS: 00007f84cd0be740(0000) GS:ffff8887ddc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555f9fbe00c8 CR3: 0000000153eec001 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kernfs_drain+0x15e/0x2f0 __kernfs_remove+0x165/0x300 kernfs_remove_by_name_ns+0x7b/0xc0 cgroup_rm_file+0x154/0x1c0 cgroup_addrm_files+0x1c2/0x1f0 css_clear_dir+0x77/0x110 kill_css+0x4c/0x1b0 cgroup_destroy_locked+0x194/0x380 cgroup_rmdir+0x2a/0x140

It can be explained by: rmdir echo 1 > cpuset.cpus kernfs_fop_write_iter // active=0 cgroup_rm_file kernfs_remove_by_name_ns kernfs_get_active // active=1 __kernfs_remove // active=0x80000002 kernfs_drain cpuset_write_resmask wait_event //waiting (active == 0x80000001) kernfs_break_active_protection // active = 0x80000001 // continue kernfs_unbreak_active_protection // active = 0x80000002 ... kernfs_should_drain_open_files // warning occurs kernfs_put_active

This warning is caused by 'kernfs_break_active_protection' when it is writing to cpuset.cpus, and the cgroup is removed concurrently.

The commit 3a5a6d0c2b03 ("cpuset: don't nest cgroup_mutex inside get_online_cpus()") made cpuset_hotplug_workfn asynchronous, This change involves calling flush_work(), which can create a multiple processes circular locking dependency that involve cgroup_mutex, potentially leading to a deadlock. To avoid deadlock. the commit 76bb5ab8f6e3 ("cpuset: break kernfs active protection in cpuset_write_resmask()") added 'kernfs_break_active_protection' in the cpuset_write_resmask. This could lead to this warning.

After the commit 2125c0034c5d ("cgroup/cpuset: Make cpuset hotplug processing synchronous"), the cpuset_write_resmask no longer needs to wait the hotplug to finish, which means that concurrent hotplug and cpuset operations are no longer possible. Therefore, the deadlock doesn't exist anymore and it does not have to 'break active protection' now. To fix this warning, just remove kernfs_break_active_protection operation in the 'cpuset_write_resmask'.

CVSS v3
5.5
EG Score
5.5MEDIUMmedium confidence
EG Risk
25
EG Risk 25/100

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)
Severity55% × 45%
Impact severity (EG Severity): CVSS 5.5 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 every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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
3rd
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 (5.5): severity, escalated by confirmed exploitation. This CVE's 5.5 is its impact severity (EG Severity), not escalated.

EG Severity
5.5 MEDIUMCVSS-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. 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (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

January 19, 2025

Last Modified

October 1, 2025

References (2)

Vendor Advisories for CVE-2025-21634(1)

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

Patch Availability(17)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulinux-tools-lowlatency-64k (6.11.0-1011.12) @ oracular2026-10-24ubuntu
ubuntulinux-tools-gke (6.8.0-1025.29) @ noble2026-10-24ubuntu
ubuntulinux-tools-oem-24.04a (6.8.0-1028.28) @ noble2026-10-24ubuntu
ubuntulinux-tools-raspi (6.11.0-1010.10) @ oracular2026-10-24ubuntu
ubuntulinux-tools-oem-24.04b (6.11.0-1017.17) @ noble2026-10-24ubuntu
ubuntulinux-tools-realtime (6.8.1-1022.23) @ noble2026-10-24ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k (6.8.0-1028.31.1) @ noble2026-10-24ubuntu
ubuntulinux-tools-azure-nvidia (6.8.0-1016.17) @ noble2026-10-24ubuntu
ubuntulinux-tools-raspi (6.8.0-1028.32) @ noble2026-10-24ubuntu
ubuntulinux-tools-gkeop-6.8 (6.8.0-1012.14) @ noble2026-10-24ubuntu
ubuntulinux-tools-raspi-realtime (6.8.0-2023.24) @ noble2026-10-24ubuntu
ubuntulinux-virtual (6.8.0-60.63) @ noble2026-10-24ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.11.0-21.21) @ oracular2026-10-24ubuntu
ubuntulinux-tools-lowlatency-hwe-24.04-edge (6.11.0-1011.12~24.04.1) @ noble2026-10-24ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-60.63~22.04.1) @ jammy2026-10-24ubuntu
ubuntulinux-tools-oracle-edge (6.8.0-1026.27~22.04.1) @ jammy2026-10-24ubuntu
linuxKernel @ 6.12.10 (fixes >=3.16.0)—osv

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

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
linux5.10.103-1 ... 7.2~rc5-1~exp1 (496 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
linux6.1.106-1 ... 7.2~rc7-1~exp1 (350 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.12.10-1: fixed in 6.12.10-1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
linux—
  • every version up to 6.12.10-1: fixed in 6.12.10-1
—

Weakness Classification(1)

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

All Vendor Advisories

(16)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 7× in last 7d / 39× 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 96 of 193 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. 4 repeat rows among the latest 100 are merged into the row they repeat. The 97 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
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  11. 2026-10-24 01:16 UTCEG score recompute
  12. 2026-10-24 01:16 UTCVendor advisory
  13. 2026-10-24 01:16 UTCGHSA enrichmentGHSA-v62x-6v8m-46vv · GitHub CVSS 5.5
  14. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
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  20. 2026-10-18 05:46 UTCEG score recompute
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  1. 2026-10-12 17:19 UTCEG score recompute
  2. 2026-10-12 16:32 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
  3. 2026-10-11 20:51 UTCEG score recompute
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  6. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
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  30. 2026-09-13 23:19 UTCOSV refresh
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  46. 2026-08-26 00:39 UTCOSV refresh
  47. 2026-08-25 13:47 UTCEPSS rescoreEPSS 0.1% · 3rd percentile
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  60. 2026-08-09 17:09 UTCOSV refresh
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Frequently asked(5)

What is CVE-2025-21634?
CVE-2025-21634 is a medium-severity vulnerability; its CVE record was published on January 19, 2025. In the Linux kernel, the following vulnerability has been resolved: cgroup/cpuset: remove kernfs active break A warning was found: WARNING: CPU: 10 PID: 3486953 at fs/kernfs/file.c:828 CPU: 10 PID: 3486953 Comm: rmdir Kdump: loaded Tainted: G RIP: 0010:kernfs_should_drain_open_files+0x1a1/0x1b0…
When was the CVE record for CVE-2025-21634 published?
The CVE record for CVE-2025-21634 was published on January 19, 2025. 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 1, 2025; the record at its source may have been updated since.
Is CVE-2025-21634 actively exploited?
CVE-2025-21634 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (3rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-21634?
CVE-2025-21634 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-21634?
A fix for CVE-2025-21634 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2025-21634 are linked in the Vendor Advisories panel on this page.

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