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Full vulnerability report · 2026
CVE-2026-64091High confidence

batman-adv: tt: fix TOCTOU race for reported vlans

Linux · Linux

9.8CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 9 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 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-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 9 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 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
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 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-2026-45776

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 72 hours

Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.

Patch available
01

What, why and how

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: fix TOCTOU race for reported vlans The local TT based TVLV is generated by first checking the number of VLANs which have at least one TT entry. A new buffer with the correct size for the VLANs is then allocated. Only then, the list of VLANs s used to fill the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock is held. But the actual number of TT entries of each VLAN can still increase during this time - just not the number of VLANs in the list. But the prefilter used in the buffer size calculation might still cause an increase of the number of VLANs which need to be stored. Simply because a VLAN might now suddenly have at least one entry when it had none in the pre-alloc check - and then needs to occupy space which was not allocated. It is better to overestimate the buffer size at the beginning and then fill the buffer only with the VLANs which are not empty.

What

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: fix TOCTOU race for reported vlans The local TT based TVLV is generated by first checking the number of VLANs which have at least one TT entry. A new buffer with the correct size for the VLANs is then allocated. Only then, the list of VLANs s used to fill the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock is held. But the actual number of TT entries of each VLAN can still increase during this time - just not the number of VLANs in the list. But the prefilter used in the buffer size calculation might still cause an increase of the number of VLANs which need to be stored. Simply because a VLAN might now suddenly have at least one entry when it had none in the pre-alloc check - and then needs to occupy space which was not allocated. It is better to overestimate the buffer size at the beginning and then fill the buffer only with the VLANs which are not empty.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. 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: batman-adv: tt: fix TOCTOU race for reported vlans The local TT based TVLV is generated by first checking the number of VLANs which have at least one TT entry. A new buffer with the correct size for the VLANs is then allocated. Only then, the list of VLANs s used to fill the VLAN entries in the buffer. During this time, the meshif_vlan_list_lock is held. But the actual number of TT entries of each VLAN can still increase during this time - just not the number of VLANs in the list. But the prefilter used in the buffer size calculation might still cause an increase of the number of VLANs which need to be stored. Simply because a VLAN might now suddenly have at least one entry when it had none in the pre-alloc check - and then needs to occupy space which was not allocated. It is better to overestimate the buffer size at the beginning and then fill the buffer only with the VLANs which are not empty.

Why

The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. 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
a network path → Time-of-check Time-of-use (TOCTOU) Race Condition → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
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: a standard category for the underlying weakness.
CWE-367

CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/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.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing 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
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.
NetworkUnauthenticatedCWE-367
A

Official authority intelligence

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

BSI · German · WID-SEC-W-2026-2403Linux Kernel: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen, möglicherweise Sicherheitsmaßnahmen zu umgehen, einen Denial-of-Service-Zustand herbeizuführen oder vertrauliche Informationen offenzulegen.

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

d?id=CVE-2026-63975 Référence CVE CVE-2026-63976 https://www.cve.org/CVERecord?id=CVE-2026-63976 Référence CVE CVE-2026-63991 https://www.cve.org/CVERecord?id=CVE-2026-63991 Référence CVE CVE-2026-63994 https://www.cve.org/CVERecord?id=CVE-2026-63994 Référence CVE CVE-2026-64018 https://www.cve.org/CVERecord?id=CVE-2026-64018 Référence CVE CVE-2026-64021 https://www.cve.org/CVERecord?id=CVE-2026-64021 Référence CVE CVE-2026-64025 https://www.cve.org/CVERecord?id=CVE-2026-64025 Référence CVE CVE-2026-64034 https://www.cve.org/CVERecord?id=CVE-2026-64034 Référence CVE CVE-2026-64061 https://www.cve.org/CVERecord?id=CVE-2026-64061 Référence CVE CVE-2026-64091 https://www.cve.org/CVERecord?id=CVE-2026-64091 Référence CVE CVE-2026-64106 https://www.cve.org/CVERecord?id=CVE-2026-64106 Référence CVE CVE-2026-64157 https://www.cve.org/CVERecord?id=CVE-2026-64157 Référence CVE CVE-2026-64158 https://www.cve.org/CVERecord?id=CVE-2026-64158 Référence CVE CVE-2026-64174 https://www.cve.org/CVERecord?id=CVE-2026-64174 Référence CVE CVE-2026-64182 https://www.cve.org/CVERecord?id=CVE-2026-64182 Référence CVE CVE-2026-64183 https://www.cve.org/CVERecord?id=CVE-2026-64183 Référence CVE CVE-2026-64187 https://www.cve.org/CVERecord?id=CVE-2026-64187 Référence CVE CVE-2026-64188 https://www.cve.org/CVERecord?id=

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

d?id=CVE-2026-64082 Référence CVE CVE-2026-64083 https://www.cve.org/CVERecord?id=CVE-2026-64083 Référence CVE CVE-2026-64084 https://www.cve.org/CVERecord?id=CVE-2026-64084 Référence CVE CVE-2026-64085 https://www.cve.org/CVERecord?id=CVE-2026-64085 Référence CVE CVE-2026-64086 https://www.cve.org/CVERecord?id=CVE-2026-64086 Référence CVE CVE-2026-64087 https://www.cve.org/CVERecord?id=CVE-2026-64087 Référence CVE CVE-2026-64088 https://www.cve.org/CVERecord?id=CVE-2026-64088 Référence CVE CVE-2026-64089 https://www.cve.org/CVERecord?id=CVE-2026-64089 Référence CVE CVE-2026-64090 https://www.cve.org/CVERecord?id=CVE-2026-64090 Référence CVE CVE-2026-64091 https://www.cve.org/CVERecord?id=CVE-2026-64091 Référence CVE CVE-2026-64093 https://www.cve.org/CVERecord?id=CVE-2026-64093 Référence CVE CVE-2026-64094 https://www.cve.org/CVERecord?id=CVE-2026-64094 Référence CVE CVE-2026-64095 https://www.cve.org/CVERecord?id=CVE-2026-64095 Référence CVE CVE-2026-64096 https://www.cve.org/CVERecord?id=CVE-2026-64096 Référence CVE CVE-2026-64097 https://www.cve.org/CVERecord?id=CVE-2026-64097 Référence CVE CVE-2026-64098 https://www.cve.org/CVERecord?id=CVE-2026-64098 Référence CVE CVE-2026-64099 https://www.cve.org/CVERecord?id=CVE-2026-64099 Référence CVE CVE-2026-64100 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-2026-64082 Référence CVE CVE-2026-64083 https://www.cve.org/CVERecord?id=CVE-2026-64083 Référence CVE CVE-2026-64084 https://www.cve.org/CVERecord?id=CVE-2026-64084 Référence CVE CVE-2026-64085 https://www.cve.org/CVERecord?id=CVE-2026-64085 Référence CVE CVE-2026-64086 https://www.cve.org/CVERecord?id=CVE-2026-64086 Référence CVE CVE-2026-64087 https://www.cve.org/CVERecord?id=CVE-2026-64087 Référence CVE CVE-2026-64088 https://www.cve.org/CVERecord?id=CVE-2026-64088 Référence CVE CVE-2026-64089 https://www.cve.org/CVERecord?id=CVE-2026-64089 Référence CVE CVE-2026-64090 https://www.cve.org/CVERecord?id=CVE-2026-64090 Référence CVE CVE-2026-64091 https://www.cve.org/CVERecord?id=CVE-2026-64091 Référence CVE CVE-2026-64093 https://www.cve.org/CVERecord?id=CVE-2026-64093 Référence CVE CVE-2026-64094 https://www.cve.org/CVERecord?id=CVE-2026-64094 Référence CVE CVE-2026-64095 https://www.cve.org/CVERecord?id=CVE-2026-64095 Référence CVE CVE-2026-64096 https://www.cve.org/CVERecord?id=CVE-2026-64096 Référence CVE CVE-2026-64097 https://www.cve.org/CVERecord?id=CVE-2026-64097 Référence CVE CVE-2026-64098 https://www.cve.org/CVERecord?id=CVE-2026-64098 Référence CVE CVE-2026-64099 https://www.cve.org/CVERecord?id=CVE-2026-64099 Référence CVE CVE-2026-64100 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-2026-64082 Référence CVE CVE-2026-64083 https://www.cve.org/CVERecord?id=CVE-2026-64083 Référence CVE CVE-2026-64084 https://www.cve.org/CVERecord?id=CVE-2026-64084 Référence CVE CVE-2026-64085 https://www.cve.org/CVERecord?id=CVE-2026-64085 Référence CVE CVE-2026-64086 https://www.cve.org/CVERecord?id=CVE-2026-64086 Référence CVE CVE-2026-64087 https://www.cve.org/CVERecord?id=CVE-2026-64087 Référence CVE CVE-2026-64088 https://www.cve.org/CVERecord?id=CVE-2026-64088 Référence CVE CVE-2026-64089 https://www.cve.org/CVERecord?id=CVE-2026-64089 Référence CVE CVE-2026-64090 https://www.cve.org/CVERecord?id=CVE-2026-64090 Référence CVE CVE-2026-64091 https://www.cve.org/CVERecord?id=CVE-2026-64091 Référence CVE CVE-2026-64093 https://www.cve.org/CVERecord?id=CVE-2026-64093 Référence CVE CVE-2026-64094 https://www.cve.org/CVERecord?id=CVE-2026-64094 Référence CVE CVE-2026-64095 https://www.cve.org/CVERecord?id=CVE-2026-64095 Référence CVE CVE-2026-64096 https://www.cve.org/CVERecord?id=CVE-2026-64096 Référence CVE CVE-2026-64097 https://www.cve.org/CVERecord?id=CVE-2026-64097 Référence CVE CVE-2026-64098 https://www.cve.org/CVERecord?id=CVE-2026-64098 Référence CVE CVE-2026-64099 https://www.cve.org/CVERecord?id=CVE-2026-64099 Référence CVE CVE-2026-64100 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
16116dac23396e73c01eeee97b102e4833a4b205 < e4236bf3ec8d6bb15d0d8d825dcf9933a7d6666b; 16116dac23396e73c01eeee97b102e4833a4b205 < 724a8eb4155669797c96b70d70e354284ae3b5a8; 16116dac23396e73c01eeee97b102e4833a4b205 < 211ea59988e1cba43cb0367ad65d379b56f9c3bd; 16116dac23396e73c01eeee97b102e4833a4b205 < 65a1e67339aa8c95ac544b796946af388930ee23; 16116dac23396e73c01eeee97b102e4833a4b205 < b4d4efd4e351593c81e9293d4b4408d244fa5ee7; 16116dac23396e73c01eeee97b102e4833a4b205 < 4cc85aec8d3c9ab4dc716dc9f1ed36fca16b227f; 16116dac23396e73c01eeee97b102e4833a4b205 < 9a9c859457bc440a55773e01ff18b1bb5bab6836; 16116dac23396e73c01eeee97b102e4833a4b205 < 94d27005016be15ffc638b2ecbc4d58805ad7b48
Fixed
< 4.17; 5.10.259 ≤ 5.10.*; 5.15.210 ≤ 5.15.*; 6.1.176 ≤ 6.1.*; 6.6.143 ≤ 6.6.*; 6.12.93 ≤ 6.12.*; 6.18.34 ≤ 6.18.*; 7.0.11 ≤ 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. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 19 Jul 2026 · Last source change 5 Aug 2026, 12:39 UTC · CWE-367 · Time-of-check Time-of-use (TOCTOU) Race Condition

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-2026-45776
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

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-2026-64091 · cve.blacktree.nl