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Full vulnerability report · 2025
CVE-2025-40327High confidence

perf/core: Fix system hang caused by cpu-clock usage

Linux · Linux

UnscoredAssess manually
Recommended action
Needs assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

11 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivelinux-aws-6.17Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azure-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gcp-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-hwe-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-lowlatency-hwe-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidia-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-oem-6.11Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-oracle-6.17Affected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspi-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-realtimeAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-riscvAffected, no fix publishedCanonical OVAL identifies this running kernel flavour as affected and does not publish a fixed package version in this definition.Not published in this feedCanonical record ↗Source updated 9 Sept 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-201875

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionNeeds assessment

No CVSS base score is available from the CNA, CISA ADP or NIST. Absence of a score is not evidence of low risk; review the vendor advisory, affected exposure and exploit evidence.

Patch available
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix system hang caused by cpu-clock usage cpu-clock usage by the async-profiler tool can trigger a system hang, which got bisected back to the following commit by Octavia Togami: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue The root cause of the hang is that cpu-clock is a special type of SW event which relies on hrtimers. The __perf_event_overflow() callback is invoked from the hrtimer handler for cpu-clock events, and __perf_event_overflow() tries to call cpu_clock_event_stop() to stop the event, which calls htimer_cancel() to cancel the hrtimer. But that's a recursion into the hrtimer code from a hrtimer handler, which (unsurprisingly) deadlocks. To fix this bug, use hrtimer_try_to_cancel() instead, and set the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer() to stop the event once it sees the PERF_HES_STOPPED flag. [ mingo: Fixed the comments and improved the changelog. ]

What

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix system hang caused by cpu-clock usage cpu-clock usage by the async-profiler tool can trigger a system hang, which got bisected back to the following commit by Octavia Togami: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue The root cause of the hang is that cpu-clock is a special type of SW event which relies on hrtimers. The __perf_event_overflow() callback is invoked from the hrtimer handler for cpu-clock events, and __perf_event_overflow() tries to call cpu_clock_event_stop() to stop the event, which calls htimer_cancel() to cancel the hrtimer. But that's a recursion into the hrtimer code from a hrtimer handler, which (unsurprisingly) deadlocks. To fix this bug, use hrtimer_try_to_cancel() instead, and set the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer() to stop the event once it sees the PERF_HES_STOPPED flag. [ mingo: Fixed the comments and improved the changelog. ]

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix system hang caused by cpu-clock usage cpu-clock usage by the async-profiler tool can trigger a system hang, which got bisected back to the following commit by Octavia Togami: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue The root cause of the hang is that cpu-clock is a special type of SW event which relies on hrtimers. The __perf_event_overflow() callback is invoked from the hrtimer handler for cpu-clock events, and __perf_event_overflow() tries to call cpu_clock_event_stop() to stop the event, which calls htimer_cancel() to cancel the hrtimer. But that's a recursion into the hrtimer code from a hrtimer handler, which (unsurprisingly) deadlocks. To fix this bug, use hrtimer_try_to_cancel() instead, and set the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer() to stop the event once it sees the PERF_HES_STOPPED flag. [ mingo: Fixed the comments and improved the changelog. ]

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through the affected interface may attempt exploitation when the stated preconditions are met. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
the affected interface → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Unspecified
Privileges required
Not stated in the selected CVSS metric
User interaction
Not stated in the selected CVSS metric
Attack complexity
Not stated in the selected CVSS metric
Security boundary
Not stated in the selected CVSS metric
Weakness
?CWE means Common Weakness Enumeration.
CWE not yet assigned
CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
Not available from the selected scoring authority.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2025-2765Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

Ein lokaler Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen.

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0227Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2025-40317 Référence CVE CVE-2025-40318 https://www.cve.org/CVERecord?id=CVE-2025-40318 Référence CVE CVE-2025-40319 https://www.cve.org/CVERecord?id=CVE-2025-40319 Référence CVE CVE-2025-40320 https://www.cve.org/CVERecord?id=CVE-2025-40320 Référence CVE CVE-2025-40321 https://www.cve.org/CVERecord?id=CVE-2025-40321 Référence CVE CVE-2025-40322 https://www.cve.org/CVERecord?id=CVE-2025-40322 Référence CVE CVE-2025-40323 https://www.cve.org/CVERecord?id=CVE-2025-40323 Référence CVE CVE-2025-40324 https://www.cve.org/CVERecord?id=CVE-2025-40324 Référence CVE CVE-2025-40326 https://www.cve.org/CVERecord?id=CVE-2025-40326 Référence CVE CVE-2025-40327 https://www.cve.org/CVERecord?id=CVE-2025-40327 Référence CVE CVE-2025-40328 https://www.cve.org/CVERecord?id=CVE-2025-40328 Référence CVE CVE-2025-40329 https://www.cve.org/CVERecord?id=CVE-2025-40329 Référence CVE CVE-2025-40330 https://www.cve.org/CVERecord?id=CVE-2025-40330 Référence CVE CVE-2025-40331 https://www.cve.org/CVERecord?id=CVE-2025-40331 Référence CVE CVE-2025-40332 https://www.cve.org/CVERecord?id=CVE-2025-40332 Référence CVE CVE-2025-40333 https://www.cve.org/CVERecord?id=CVE-2025-40333 Référence CVE CVE-2025-40334 https://www.cve.org/CVERecord?id=CVE-2025-40334 Référence CVE CVE-2025-40335 https://www.cve.org/CVERecord?id=

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0194Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2025-40317 Référence CVE CVE-2025-40318 https://www.cve.org/CVERecord?id=CVE-2025-40318 Référence CVE CVE-2025-40319 https://www.cve.org/CVERecord?id=CVE-2025-40319 Référence CVE CVE-2025-40320 https://www.cve.org/CVERecord?id=CVE-2025-40320 Référence CVE CVE-2025-40321 https://www.cve.org/CVERecord?id=CVE-2025-40321 Référence CVE CVE-2025-40322 https://www.cve.org/CVERecord?id=CVE-2025-40322 Référence CVE CVE-2025-40323 https://www.cve.org/CVERecord?id=CVE-2025-40323 Référence CVE CVE-2025-40324 https://www.cve.org/CVERecord?id=CVE-2025-40324 Référence CVE CVE-2025-40326 https://www.cve.org/CVERecord?id=CVE-2025-40326 Référence CVE CVE-2025-40327 https://www.cve.org/CVERecord?id=CVE-2025-40327 Référence CVE CVE-2025-40328 https://www.cve.org/CVERecord?id=CVE-2025-40328 Référence CVE CVE-2025-40329 https://www.cve.org/CVERecord?id=CVE-2025-40329 Référence CVE CVE-2025-40330 https://www.cve.org/CVERecord?id=CVE-2025-40330 Référence CVE CVE-2025-40331 https://www.cve.org/CVERecord?id=CVE-2025-40331 Référence CVE CVE-2025-40332 https://www.cve.org/CVERecord?id=CVE-2025-40332 Référence CVE CVE-2025-40333 https://www.cve.org/CVERecord?id=CVE-2025-40333 Référence CVE CVE-2025-40334 https://www.cve.org/CVERecord?id=CVE-2025-40334 Référence CVE CVE-2025-40335 https://www.cve.org/CVERecord?id=

Official advisory
CERT-FR · French · CERTFR-2026-AVI-0169Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2025-40317 Référence CVE CVE-2025-40318 https://www.cve.org/CVERecord?id=CVE-2025-40318 Référence CVE CVE-2025-40319 https://www.cve.org/CVERecord?id=CVE-2025-40319 Référence CVE CVE-2025-40320 https://www.cve.org/CVERecord?id=CVE-2025-40320 Référence CVE CVE-2025-40321 https://www.cve.org/CVERecord?id=CVE-2025-40321 Référence CVE CVE-2025-40322 https://www.cve.org/CVERecord?id=CVE-2025-40322 Référence CVE CVE-2025-40323 https://www.cve.org/CVERecord?id=CVE-2025-40323 Référence CVE CVE-2025-40324 https://www.cve.org/CVERecord?id=CVE-2025-40324 Référence CVE CVE-2025-40326 https://www.cve.org/CVERecord?id=CVE-2025-40326 Référence CVE CVE-2025-40327 https://www.cve.org/CVERecord?id=CVE-2025-40327 Référence CVE CVE-2025-40328 https://www.cve.org/CVERecord?id=CVE-2025-40328 Référence CVE CVE-2025-40329 https://www.cve.org/CVERecord?id=CVE-2025-40329 Référence CVE CVE-2025-40330 https://www.cve.org/CVERecord?id=CVE-2025-40330 Référence CVE CVE-2025-40331 https://www.cve.org/CVERecord?id=CVE-2025-40331 Référence CVE CVE-2025-40332 https://www.cve.org/CVERecord?id=CVE-2025-40332 Référence CVE CVE-2025-40333 https://www.cve.org/CVERecord?id=CVE-2025-40333 Référence CVE CVE-2025-40334 https://www.cve.org/CVERecord?id=CVE-2025-40334 Référence CVE CVE-2025-40335 https://www.cve.org/CVERecord?id=

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
18dbcbfabfffc4a5d3ea10290c5ad27f22b0d240 < 6b8c512811644cf2f5eaf6f44e928683c54127f0; 18dbcbfabfffc4a5d3ea10290c5ad27f22b0d240 < eb3182ef0405ff2f6668fd3e5ff9883f60ce8801; b2de0c9ce8e542b5cb4cd3944620d9dd1ea1f0ac; 6.16.8 < 6.17; 6.17
Fixed
< 6.17; 6.17.8 ≤ 6.17.*; 6.18 ≤ *
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. Limit untrusted access and use least privilege until authoritative guidance is available.
04

Evidence and provenance

Published 9 Dec 2025 · Last source change 23 May 2026, 16:02 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceUnavailable
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-201875
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD not scheduled

Missing structured fields: CVSS base score, CWE classification. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-40327 · cve.blacktree.nl