CVE-2026-68296

Local system hang via GRE transmit deadlock

Published Aug 10, 2026 · Updated Aug 10, 2026

Deadlock in affected Linux kernel releases allows local users to hang systems via SEQ- or CSUM-enabled GRE tunnel transmission. In __gre_tunnel_init() and ip6gre_tnl_init_features(), dev->lltx is set after SEQ/CSUM early returns, so affected tunnels reacquire _xmit_lock while re-entering the transmit stack and can invert lock order against the underlay device. A low-privileged local account and a GRE, GRETAP, or ip6gre tunnel using SEQ or CSUM with encapsulation are required; successful triggering leaves transmit tasks blocked and the system unresponsive.

CVSS severity5.5
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in affected Linux kernel releases allows local users to hang systems via SEQ- or CSUM-enabled GRE tunnel transmission. In __gre_tunnel_init() and ip6gre_tnl_init_features(), dev->lltx is set after SEQ/CSUM early returns, so affected tunnels reacquire _xmit_lock while re-entering the transmit stack and can invert lock order against the underlay device. A low-privileged local account and a GRE, GRETAP, or ip6gre tunnel using SEQ or CSUM with encapsulation are required; successful triggering leaves transmit tasks blocked and the system unresponsive.

The record

CVE
CVE-2026-68296
Published
Aug 10, 2026
Updated
Aug 10, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-833, CAPEC-25, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 10, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3
  2. Affected versionversion=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <2bffe379023512d280337c70faeb6a8cc435db5e
  3. Affected versionversion=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <675ed582c1aa4d919dd535490de08c015005c653
  4. Affected versionversion=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <9f948e9aede9678f4103457daf2bc9dd54c65a06
  5. Affected versionversion=6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <15a1c5f2ed2eeb3daad8d5766fd506aeda4710f3; version=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <2bffe379023512d280337c70faeb6a8cc435db5e; version=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <675ed582c1aa4d919dd535490de08c015005c653; version=00d066a4d4edbe559ba6c35153da71d4b2b8a383 <9f948e9aede9678f4103457daf2bc9dd54c65a06; version=6.12

Published CVSS scores

5.5Red HatCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-833Deadlock
CAPEC-25Forced Deadlock
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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