CVE-2026-63980Network attack vector

Remote denial of service via handshake deadlock

Published Jul 19, 2026 · Updated Jul 19, 2026

Deadlock in the Linux kernel NVMe/TCP TLS handshake allows remote attackers to hang a target host by timing connection resets. handshake_req_cancel() takes hn_lock with spin_lock() while softirqs remain enabled, so a socket callback can reenter and wait forever on the same lock. The path requires an NVMe/TCP target with TLS enabled and concurrent disconnect timing; the deadlock can soft-lock a CPU and escalate to a kernel panic.

CVSS severity7.5
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Deadlock in the Linux kernel NVMe/TCP TLS handshake allows remote attackers to hang a target host by timing connection resets. handshake_req_cancel() takes hn_lock with spin_lock() while softirqs remain enabled, so a socket callback can reenter and wait forever on the same lock. The path requires an NVMe/TCP target with TLS enabled and concurrent disconnect timing; the deadlock can soft-lock a CPU and escalate to a kernel panic.

The record

CVE
CVE-2026-63980
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-833, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 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=6.7
  2. Affected versionversion=675b453e024154dd547921c6e6d5b58747ba7e0e <06ab5978866fc2221b910347fd3e510ca8e7b1a4
  3. Affected versionversion=675b453e024154dd547921c6e6d5b58747ba7e0e <0866569fc36a56f568acd3900d354e3505932e09
  4. Affected versionversion=675b453e024154dd547921c6e6d5b58747ba7e0e <91898de9501a047ba67c6b864dcd403e00bdfbf5
  5. Affected versionversion=675b453e024154dd547921c6e6d5b58747ba7e0e <cc993e0927ec8bd98ea33377ada03295fcda0f24

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.7; version=675b453e024154dd547921c6e6d5b58747ba7e0e <06ab5978866fc2221b910347fd3e510ca8e7b1a4; version=675b453e024154dd547921c6e6d5b58747ba7e0e <0866569fc36a56f568acd3900d354e3505932e09; version=675b453e024154dd547921c6e6d5b58747ba7e0e <91898de9501a047ba67c6b864dcd403e00bdfbf5; version=675b453e024154dd547921c6e6d5b58747ba7e0e <cc993e0927ec8bd98ea33377ada03295fcda0f24

Published CVSS scores

7.5LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-833Deadlock
T1499Endpoint Denial of Service

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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