BlackTreeIndependent security intelligence

Full vulnerability report · 2026

CVE-2026-68296High confidence

net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM

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.

13 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 release	Source package	Vendor state	Fixed version	Evidence
Ubuntu 24.04 LTSnoble · standard archive	`linux-aws-6.14`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-fde-6.14`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-azure-nvidia-6.14`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-gcp-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-hwe-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-lowlatency-hwe-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-nvidia-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oem-6.11`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-oracle-6.14`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-raspi-realtime`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-realtime`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026
Ubuntu 24.04 LTSnoble · standard archive	`linux-riscv`	Affected, 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 feed`	Canonical record ↗Source updated 9 Sept 2026

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current

CVE-2026-68296 · CSAF 2.0 · revision 3 · finalRed Hat Product Securitykernel: net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM

183 known affected

The vendor explicitly identifies these products as affected by this CVE.

kernel as a component of Red Hat Enterprise Linux 10
kernel-64k as a component of Red Hat Enterprise Linux 10
kernel-64k-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10
kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10
kernel-64k-devel as a component of Red Hat Enterprise Linux 10
kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10

Summary: A flaw was found in the Linux kernel's Generic Routing Encapsulation (GRE) tunnel implementation. An issue with how lockless transmission was handled for GRE tunnels with Sequence Number (SEQ) or Checksum (CSUM) features could lead to a deadlock. This deadlock occurs when the GRE transmit function re-enters the network stack, potentially causing the system to become unresponsive, resulting in a Denial of Service (DoS).
Remediation: Fix deferred

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-2026-55397

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

What, why and how

In the Linux kernel, the following vulnerability has been resolved: net: gre: fix lltx regression for GRE tunnels with SEQ/CSUM Before commit 00d066a4d4ed ("netdev_features: convert NETIF_F_LLTX to dev->lltx"), NETIF_F_LLTX was set unconditionally in both __gre_tunnel_init() and ip6gre_tnl_init_features() alongside GRE_FEATURES: dev->features |= GRE_FEATURES | NETIF_F_LLTX; When that commit converted NETIF_F_LLTX to the dev->lltx flag, it placed 'dev->lltx = true' after the SEQ/CSUM early returns instead of before them. This causes GRE/GRETAP/ip6gre tunnels with SEQ or CSUM+encap to lose lockless TX, reintroducing _xmit_lock acquisition around their ndo_start_xmit. Since GRE xmit re-enters the stack via ip_tunnel_xmit(), holding _xmit_lock risks ABBA deadlock with the underlay device. CPU0 CPU1 ---- ---- lock(&qdisc_xmit_lock_key#6); lock(&qdisc_xmit_lock_key#3); lock(&qdisc_xmit_lock_key#6); lock(&qdisc_xmit_lock_key#3); Fix by moving dev->lltx = true before the early returns in both functions, restoring the original unconditional behavior.

What

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

Why

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

How

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.

Official authority intelligence

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

ENISA EUVD · EUVD-2026-55397Official EUVD mapping

0 linked advisory records.

Official EUVD record

BSI · German · WID-SEC-W-2026-2730Linux Kernel: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen, darunter möglicherweise die Ausführung von beliebigem Code, die Ausweitung von Berechtigungen, die Offenlegung von Informationen, die Manipulation von Daten oder Denial-of-Service-Zustände.

Official advisory

CERT-FR · French · CERTFR-2026-AVI-1069Multiples vulnérabilités dans le noyau Linux de Debian LTS

d?id=CVE-2026-68277 Référence CVE CVE-2026-68278 https://www.cve.org/CVERecord?id=CVE-2026-68278 Référence CVE CVE-2026-68279 https://www.cve.org/CVERecord?id=CVE-2026-68279 Référence CVE CVE-2026-68280 https://www.cve.org/CVERecord?id=CVE-2026-68280 Référence CVE CVE-2026-68281 https://www.cve.org/CVERecord?id=CVE-2026-68281 Référence CVE CVE-2026-68284 https://www.cve.org/CVERecord?id=CVE-2026-68284 Référence CVE CVE-2026-68290 https://www.cve.org/CVERecord?id=CVE-2026-68290 Référence CVE CVE-2026-68293 https://www.cve.org/CVERecord?id=CVE-2026-68293 Référence CVE CVE-2026-68294 https://www.cve.org/CVERecord?id=CVE-2026-68294 Référence CVE CVE-2026-68296 https://www.cve.org/CVERecord?id=CVE-2026-68296 Référence CVE CVE-2026-68297 https://www.cve.org/CVERecord?id=CVE-2026-68297 Référence CVE CVE-2026-68299 https://www.cve.org/CVERecord?id=CVE-2026-68299 Référence CVE CVE-2026-68300 https://www.cve.org/CVERecord?id=CVE-2026-68300 Référence CVE CVE-2026-68301 https://www.cve.org/CVERecord?id=CVE-2026-68301 Référence CVE CVE-2026-68302 https://www.cve.org/CVERecord?id=CVE-2026-68302 Référence CVE CVE-2026-68304 https://www.cve.org/CVERecord?id=CVE-2026-68304 Référence CVE CVE-2026-68306 https://www.cve.org/CVERecord?id=CVE-2026-68306 Référence CVE CVE-2026-68307 https://www.cve.org/CVERecord?id=

Official advisory

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: kernel as a component of Red Hat Enterprise Linux 10; kernel-64k as a component of Red Hat Enterprise Linux 10; kernel-64k-core as a component of Red Hat Enterprise Linux 10; kernel-64k-debug as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-core as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-devel as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-devel-matched as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-modules as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-modules-core as a component of Red Hat Enterprise Linux 10; kernel-64k-debug-modules-extra as a component of Red Hat Enterprise Linux 10; kernel-64k-devel as a component of Red Hat Enterprise Linux 10; kernel-64k-devel-matched as a component of Red Hat Enterprise Linux 10; kernel-64k-modules as a component of Red Hat Enterprise Linux 10; kernel-64k-modules-core as a component of Red Hat Enterprise Linux 10; kernel-64k-modules-extra as a component of Red Hat Enterprise Linux 10; kernel-abi-stablelists as a component of Red Hat Enterprise Linux 10; kernel-core as a component of Red Hat Enterprise Linux 10; kernel-debug as a component of Red Hat Enterprise Linux 10; kernel-debug-core as a component of Red Hat Enterprise Linux 10; kernel-debug-devel as a component of Red Hat Enterprise Linux 10; kernel-debug-devel-matched as a component of Red Hat Enterprise Linux 10; kernel-debug-modules as a component of Red Hat Enterprise Linux 10; kernel-debug-modules-core as a component of Red Hat Enterprise Linux 10; kernel-debug-modules-extra as a component of Red Hat Enterprise Linux 10; kernel-debug-uki-virt as a component of Red Hat Enterprise Linux 10; kernel-devel as a component of Red Hat Enterprise Linux 10; kernel-devel-matched as a component of Red Hat Enterprise Linux 10; kernel-doc as a component of Red Hat Enterprise Linux 10; kernel-modules as a component of Red Hat Enterprise Linux 10; kernel-modules-core as a component of Red Hat Enterprise Linux 10; and 153 more
Fixed: < 6.12; 6.12.101 ≤ 6.12.*; 6.18.42 ≤ 6.18.*; 7.1.6 ≤ 7.1.*; 7.2 ≤ *
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.

Evidence and provenance

Published 10 Aug 2026 · Last source change 17 Aug 2026, 05:02 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-2026-55397

Product sourceVendor CSAF · Red Hat Product Security

Remediation sourceVendor CSAF · Red Hat Product Security

CWE sourceUnavailable

NVD statusNVD received

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 →

17 Aug 2026, 05:02 UTC
Affected versionsThe structured affected or fixed version information changed.
Before
00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 9f948e9aede9678f4103457daf2bc9dd54c65a06; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 2bffe379023512d280337c70faeb6a8cc435db5e; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 675ed582c1aa4d919dd535490de08c015005c653; 6.12 · Fixed: < 6.12; 6.12.101 ≤ 6.12.*; 6.18.42 ≤ 6.18.*; 7.1.6 ≤ 7.1.*; 7.2-rc5 ≤ *
After
00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 9f948e9aede9678f4103457daf2bc9dd54c65a06; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 2bffe379023512d280337c70faeb6a8cc435db5e; 00d066a4d4edbe559ba6c35153da71d4b2b8a383 < 675ed582c1aa4d919dd535490de08c015005c653; 6.12 · Fixed: < 6.12; 6.12.101 ≤ 6.12.*; 6.18.42 ≤ 6.18.*; 7.1.6 ≤ 7.1.*; 7.2 ≤ *
CNA ↗

2026-08-10CVE published

2026-08-17Fixed release or patch reference recorded

ENISA EUVD · EUVD-2026-55397↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗

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.