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Full vulnerability report · 2026
CVE-2026-43091High confidence

xfrm: Wait for RCU readers during policy netns exit

Linux · Linux

7.8HighCVSS 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.

20 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 archivelinuxAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-awsAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azureAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azure-fdeAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-azure-nvidiaAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gcpAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gkeAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-gkeopAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-ibmAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-lowlatencyAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidiaAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidia-lowlatencyAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-nvidia-tegraAffected, 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 11 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-oracleAffected, 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-raspiAffected, 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 11 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 11 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 11 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 11 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivelinux-xilinxAffected, 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 11 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-2026-27592

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: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables.

What

In the Linux kernel, the following vulnerability has been resolved: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables.

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: xfrm: Wait for RCU readers during policy netns exit xfrm_policy_fini() frees the policy_bydst hash tables after flushing the policy work items and deleting all policies, but it does not wait for concurrent RCU readers to leave their read-side critical sections first. The policy_bydst tables are published via rcu_assign_pointer() and are looked up through rcu_dereference_check(), so netns teardown must also wait for an RCU grace period before freeing the table memory. Fix this by adding synchronize_rcu() before freeing the policy hash tables.

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:H/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.IHighIntegrity impact: A successful attack can cause a major loss.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.

BSI · German · WID-SEC-2026-1385Linux Kernel: Mehrere Schwachstellen

Ein lokaler Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen Denial of Service zu verursachen, Informationen offenzulegen, Sicherheitsmaßnahmen zu umgehen oder potentiell beliebigen Programmcode auszuführen.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1066Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43080 Référence CVE CVE-2026-43081 https://www.cve.org/CVERecord?id=CVE-2026-43081 Référence CVE CVE-2026-43082 https://www.cve.org/CVERecord?id=CVE-2026-43082 Référence CVE CVE-2026-43083 https://www.cve.org/CVERecord?id=CVE-2026-43083 Référence CVE CVE-2026-43084 https://www.cve.org/CVERecord?id=CVE-2026-43084 Référence CVE CVE-2026-43085 https://www.cve.org/CVERecord?id=CVE-2026-43085 Référence CVE CVE-2026-43086 https://www.cve.org/CVERecord?id=CVE-2026-43086 Référence CVE CVE-2026-43088 https://www.cve.org/CVERecord?id=CVE-2026-43088 Référence CVE CVE-2026-43089 https://www.cve.org/CVERecord?id=CVE-2026-43089 Référence CVE CVE-2026-43091 https://www.cve.org/CVERecord?id=CVE-2026-43091 Référence CVE CVE-2026-43092 https://www.cve.org/CVERecord?id=CVE-2026-43092 Référence CVE CVE-2026-43093 https://www.cve.org/CVERecord?id=CVE-2026-43093 Référence CVE CVE-2026-43094 https://www.cve.org/CVERecord?id=CVE-2026-43094 Référence CVE CVE-2026-43098 https://www.cve.org/CVERecord?id=CVE-2026-43098 Référence CVE CVE-2026-43099 https://www.cve.org/CVERecord?id=CVE-2026-43099 Référence CVE CVE-2026-43103 https://www.cve.org/CVERecord?id=CVE-2026-43103 Référence CVE CVE-2026-43104 https://www.cve.org/CVERecord?id=CVE-2026-43104 Référence CVE CVE-2026-43105 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-1064Multiples vulnérabilités dans le noyau Linux de SUSE

d?id=CVE-2026-43058 Référence CVE CVE-2026-43059 https://www.cve.org/CVERecord?id=CVE-2026-43059 Référence CVE CVE-2026-43061 https://www.cve.org/CVERecord?id=CVE-2026-43061 Référence CVE CVE-2026-43062 https://www.cve.org/CVERecord?id=CVE-2026-43062 Référence CVE CVE-2026-43064 https://www.cve.org/CVERecord?id=CVE-2026-43064 Référence CVE CVE-2026-43069 https://www.cve.org/CVERecord?id=CVE-2026-43069 Référence CVE CVE-2026-43072 https://www.cve.org/CVERecord?id=CVE-2026-43072 Référence CVE CVE-2026-43077 https://www.cve.org/CVERecord?id=CVE-2026-43077 Référence CVE CVE-2026-43079 https://www.cve.org/CVERecord?id=CVE-2026-43079 Référence CVE CVE-2026-43091 https://www.cve.org/CVERecord?id=CVE-2026-43091 Référence CVE CVE-2026-43098 https://www.cve.org/CVERecord?id=CVE-2026-43098 Référence CVE CVE-2026-43104 https://www.cve.org/CVERecord?id=CVE-2026-43104 Référence CVE CVE-2026-43105 https://www.cve.org/CVERecord?id=CVE-2026-43105 Référence CVE CVE-2026-43108 https://www.cve.org/CVERecord?id=CVE-2026-43108 Référence CVE CVE-2026-43110 https://www.cve.org/CVERecord?id=CVE-2026-43110 Référence CVE CVE-2026-43111 https://www.cve.org/CVERecord?id=CVE-2026-43111 Référence CVE CVE-2026-43113 https://www.cve.org/CVERecord?id=CVE-2026-43113 Référence CVE CVE-2026-43114 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0954Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43080 Référence CVE CVE-2026-43081 https://www.cve.org/CVERecord?id=CVE-2026-43081 Référence CVE CVE-2026-43082 https://www.cve.org/CVERecord?id=CVE-2026-43082 Référence CVE CVE-2026-43083 https://www.cve.org/CVERecord?id=CVE-2026-43083 Référence CVE CVE-2026-43084 https://www.cve.org/CVERecord?id=CVE-2026-43084 Référence CVE CVE-2026-43085 https://www.cve.org/CVERecord?id=CVE-2026-43085 Référence CVE CVE-2026-43086 https://www.cve.org/CVERecord?id=CVE-2026-43086 Référence CVE CVE-2026-43088 https://www.cve.org/CVERecord?id=CVE-2026-43088 Référence CVE CVE-2026-43089 https://www.cve.org/CVERecord?id=CVE-2026-43089 Référence CVE CVE-2026-43091 https://www.cve.org/CVERecord?id=CVE-2026-43091 Référence CVE CVE-2026-43092 https://www.cve.org/CVERecord?id=CVE-2026-43092 Référence CVE CVE-2026-43093 https://www.cve.org/CVERecord?id=CVE-2026-43093 Référence CVE CVE-2026-43094 https://www.cve.org/CVERecord?id=CVE-2026-43094 Référence CVE CVE-2026-43098 https://www.cve.org/CVERecord?id=CVE-2026-43098 Référence CVE CVE-2026-43099 https://www.cve.org/CVERecord?id=CVE-2026-43099 Référence CVE CVE-2026-43103 https://www.cve.org/CVERecord?id=CVE-2026-43103 Référence CVE CVE-2026-43104 https://www.cve.org/CVERecord?id=CVE-2026-43104 Référence CVE CVE-2026-43105 https://www.cve.org/CVERecord?id=

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0926Multiples vulnérabilités dans le noyau Linux d'Ubuntu

d?id=CVE-2026-43080 Référence CVE CVE-2026-43081 https://www.cve.org/CVERecord?id=CVE-2026-43081 Référence CVE CVE-2026-43082 https://www.cve.org/CVERecord?id=CVE-2026-43082 Référence CVE CVE-2026-43083 https://www.cve.org/CVERecord?id=CVE-2026-43083 Référence CVE CVE-2026-43084 https://www.cve.org/CVERecord?id=CVE-2026-43084 Référence CVE CVE-2026-43085 https://www.cve.org/CVERecord?id=CVE-2026-43085 Référence CVE CVE-2026-43086 https://www.cve.org/CVERecord?id=CVE-2026-43086 Référence CVE CVE-2026-43088 https://www.cve.org/CVERecord?id=CVE-2026-43088 Référence CVE CVE-2026-43089 https://www.cve.org/CVERecord?id=CVE-2026-43089 Référence CVE CVE-2026-43091 https://www.cve.org/CVERecord?id=CVE-2026-43091 Référence CVE CVE-2026-43092 https://www.cve.org/CVERecord?id=CVE-2026-43092 Référence CVE CVE-2026-43093 https://www.cve.org/CVERecord?id=CVE-2026-43093 Référence CVE CVE-2026-43094 https://www.cve.org/CVERecord?id=CVE-2026-43094 Référence CVE CVE-2026-43098 https://www.cve.org/CVERecord?id=CVE-2026-43098 Référence CVE CVE-2026-43099 https://www.cve.org/CVERecord?id=CVE-2026-43099 Référence CVE CVE-2026-43103 https://www.cve.org/CVERecord?id=CVE-2026-43103 Référence CVE CVE-2026-43104 https://www.cve.org/CVERecord?id=CVE-2026-43104 Référence CVE CVE-2026-43105 https://www.cve.org/CVERecord?id=

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2026-016541LinuxのLinux Kernelにおける不特定の脆弱性

Linuxカーネルにおいて、以下の脆弱性が修正されました。xfrm: ポリシーネットワーク名前空間(netns)終了時にRCUリーダーの終了を待機します。xfrm_policy_fini()は、ポリシーワークアイテムのフラッシュとすべてのポリシーの削除後にpolicy_bydstハッシュテーブルを解放しますが、同時に動作しているRCUリーダーがリードサイドのクリティカルセクションを終了するのを待っていませんでした。policy_bydstテーブルはrcu_assign_pointer()によって公開され、rcu_dereference_check()を通じて参照されるため、ネットワーク名前空間の終了処理でもメモリ解放前にRCUの猶予期間を待つ必要があります。この問題は、policyハッシュテーブルを解放する前にsynchronize_rcu()を追加することで修正されました。

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
Linux: e1e551bc56302b80ff930c966f9985095fb1b70d < b66920a3348c0f63ba18365248fa21fbf0b3a937, e1e551bc56302b80ff930c966f9985095fb1b70d < 438b1f668ad58f46ce699bb48e4698a7839e3f9e, e1e551bc56302b80ff930c966f9985095fb1b70d < 3733fce2871c9bca9dd18a1a23b1432ea215a094, e1e551bc56302b80ff930c966f9985095fb1b70d < 33a3149dd81a1e2f52b80ee1e0fc380b39f3d028, e1e551bc56302b80ff930c966f9985095fb1b70d < 069daad4f2ae9c5c108131995529d5f02392c446, 4.9
Fixed
Linux: < 4.9, 6.6.136 ≤ 6.6.*, 6.12.83 ≤ 6.12.*, 6.18.24 ≤ 6.18.*, 6.19.14 ≤ 6.19.*, 7.0 ≤ *
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 6 May 2026 · Last source change 5 Aug 2026, 12:25 UTC · CWE not yet assigned

CVE recordCVE.org · 5.2
CVSS sourceCNA
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-2026-27592
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-2026-43091 · cve.blacktree.nl