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Full vulnerability report · 2024
CVE-2021-47262High confidence

KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message

Linux · Linux

7.1HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

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

1 package state
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-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 10 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-2021-34267

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 actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message Use the __string() machinery provided by the tracing subystem to make a copy of the string literals consumed by the "nested VM-Enter failed" tracepoint. A complete copy is necessary to ensure that the tracepoint can't outlive the data/memory it consumes and deference stale memory. Because the tracepoint itself is defined by kvm, if kvm-intel and/or kvm-amd are built as modules, the memory holding the string literals defined by the vendor modules will be freed when the module is unloaded, whereas the tracepoint and its data in the ring buffer will live until kvm is unloaded (or "indefinitely" if kvm is built-in). This bug has existed since the tracepoint was added, but was recently exposed by a new check in tracing to detect exactly this type of bug. fmt: '%s%s ' current_buffer: ' vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_failed: ' WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0 CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184 Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014 RIP: 0010:trace_check_vprintf+0x3be/0x3e0 Code: <0f> 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20 RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8 RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8 R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4 R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000 FS: 00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0 Call Trace: trace_event_printf+0x5e/0x80 trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm] print_trace_line+0x1dd/0x4e0 s_show+0x45/0x150 seq_read_iter+0x2d5/0x4c0 seq_read+0x106/0x150 vfs_read+0x98/0x180 ksys_read+0x5f/0xe0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae

What

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message Use the __string() machinery provided by the tracing subystem to make a copy of the string literals consumed by the "nested VM-Enter failed" tracepoint. A complete copy is necessary to ensure that the tracepoint can't outlive the data/memory it consumes and deference stale memory. Because the tracepoint itself is defined by kvm, if kvm-intel and/or kvm-amd are built as modules, the memory holding the string literals defined by the vendor modules will be freed when the module is unloaded, whereas the tracepoint and its data in the ring buffer will live until kvm is unloaded (or "indefinitely" if kvm is built-in). This bug has existed since the tracepoint was added, but was recently exposed by a new check in tracing to detect exactly this type of bug. fmt: '%s%s ' current_buffer: ' vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_failed: ' WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0 CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184 Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014 RIP: 0010:trace_check_vprintf+0x3be/0x3e0 Code: <0f> 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20 RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8 RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8 R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4 R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000 FS: 00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0 Call Trace: trace_event_printf+0x5e/0x80 trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm] print_trace_line+0x1dd/0x4e0 s_show+0x45/0x150 seq_read_iter+0x2d5/0x4c0 seq_read+0x106/0x150 vfs_read+0x98/0x180 ksys_read+0x5f/0xe0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae

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 local access may attempt exploitation with low privileges. 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: KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message Use the __string() machinery provided by the tracing subystem to make a copy of the string literals consumed by the "nested VM-Enter failed" tracepoint. A complete copy is necessary to ensure that the tracepoint can't outlive the data/memory it consumes and deference stale memory. Because the tracepoint itself is defined by kvm, if kvm-intel and/or kvm-amd are built as modules, the memory holding the string literals defined by the vendor modules will be freed when the module is unloaded, whereas the tracepoint and its data in the ring buffer will live until kvm is unloaded (or "indefinitely" if kvm is built-in). This bug has existed since the tracepoint was added, but was recently exposed by a new check in tracing to detect exactly this type of bug. fmt: '%s%s ' current_buffer: ' vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_failed: ' WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0 CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184 Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014 RIP: 0010:trace_check_vprintf+0x3be/0x3e0 Code: <0f> 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20 RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027 RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8 RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8 R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4 R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000 FS: 00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0 Call Trace: trace_event_printf+0x5e/0x80 trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm] print_trace_line+0x1dd/0x4e0 s_show+0x45/0x150 seq_read_iter+0x2d5/0x4c0 seq_read+0x106/0x150 vfs_read+0x98/0x180 ksys_read+0x5f/0xe0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae

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 local access may attempt exploitation with low privileges. 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
local access → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Local
Privileges required
Low: a basic authenticated account is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
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.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVLocalAttack vector: The attacker needs local access to the vulnerable system.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRLowPrivileges required: The attacker needs basic user-level privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
The issue can support a local privilege or sandbox boundary transition; normal system utilities may then be available in the gained context.
A

Official authority intelligence

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

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
380e0055bc7e4a5c687436ba3ccebb4667836b95 < 796d3bd4ac9316e70c181189318cd2bd98af34bc; 380e0055bc7e4a5c687436ba3ccebb4667836b95 < d046f724bbd725a24007b7e52b2d675249870888; 380e0055bc7e4a5c687436ba3ccebb4667836b95 < 9fb088ce13bc3c59a51260207b487db3e556f275; 380e0055bc7e4a5c687436ba3ccebb4667836b95 < f31500b0d437a2464ca5972d8f5439e156b74960; 5.4
Fixed
< 5.4; 5.4.126 ≤ 5.4.*; 5.10.44 ≤ 5.10.*; 5.12.11 ≤ 5.12.*; 5.13 ≤ *
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 21 May 2024 · Last source change 11 May 2026, 13:51 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
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-2021-34267
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD enriched

Missing structured fields: 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-2021-47262 · cve.blacktree.nl