Linux Kernel up to 6.12.100/6.18.41/7.1.5/7.2-rc4 GRE Tunnels __gre_tunnel_init/ip6gre_tnl_init_features deadlock

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.2$0-$5k0.83-

Summaryinfo

A vulnerability described as critical has been identified in Linux Kernel up to 6.12.100/6.18.41/7.1.5/7.2-rc4. Affected by this issue is the function __gre_tunnel_init/ip6gre_tnl_init_features of the component GRE Tunnels. The manipulation results in deadlock. This vulnerability is known as CVE-2026-68296. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.12.100/6.18.41/7.1.5/7.2-rc4. Affected is the function __gre_tunnel_init/ip6gre_tnl_init_features of the component GRE Tunnels. The manipulation with an unknown input leads to a deadlock vulnerability. CWE is classifying the issue as CWE-833. The product contains multiple threads or executable segments that are waiting for each other to release a necessary lock, resulting in deadlock. This is going to have an impact on availability. CVE summarizes:

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.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-68296 since 07/30/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/10/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 6.12.101, 6.18.42, 7.1.6 or 7.2-rc5 eliminates this vulnerability. Applying the patch 9f948e9aede9678f4103457daf2bc9dd54c65a06/15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3/2bffe379023512d280337c70faeb6a8cc435db5e/675ed582c1aa4d919dd535490de08c015005c653 is able to eliminate this problem.

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Productinfo

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Vendor

Name

Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Deadlock
CWE: CWE-833 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.12.101/6.18.42/7.1.6/7.2-rc5
Patch: 9f948e9aede9678f4103457daf2bc9dd54c65a06/15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3/2bffe379023512d280337c70faeb6a8cc435db5e/675ed582c1aa4d919dd535490de08c015005c653

Timelineinfo

07/30/2026 CVE reserved
08/10/2026 +11 days Advisory disclosed
08/10/2026 +0 days VulDB entry created
08/10/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-68296 (🔒)
GCVE (CVE): GCVE-0-2026-68296
GCVE (VulDB): GCVE-100-387630

Entryinfo

Created: 08/10/2026 16:57
Changes: 08/10/2026 16:57 (59)
Complete: 🔍
Cache ID: 216::103

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