CVE-2026-64534Network attack vector

Kernel compromise via unbalanced reference release

Published Jul 27, 2026 · Updated Jul 27, 2026

Memory corruption in Linux Kernel nvmet-tcp allows remote attackers to compromise a target through malformed NVMe/TCP traffic. The digest-error path in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit() after initialization has failed, causing percpu_ref_put() to release an unacquired reference and underflow the count. A reachable NVMe/TCP target with data digests enabled is required; the underflow can deadlock workqueues, crash the kernel, expose reused kernel memory, or corrupt kernel state.

CVSS severity9.8
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory corruption in Linux Kernel nvmet-tcp allows remote attackers to compromise a target through malformed NVMe/TCP traffic. The digest-error path in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit() after initialization has failed, causing percpu_ref_put() to release an unacquired reference and underflow the count. A reachable NVMe/TCP target with data digests enabled is required; the underflow can deadlock workqueues, crash the kernel, expose reused kernel memory, or corrupt kernel state.

The record

CVE
CVE-2026-64534
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-911, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0 <5.10.261
  2. Affected versionversion=0 <5.15.212
  3. Affected versionversion=0 <6.1.178
  4. Affected versionversion=0 <6.12.97
  5. Affected versionversion=0 <6.18.40
  6. Affected versionversion=0 <6.6.145
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2ed3c9d955e8cd6361f130623baa664a75fb345f
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4606467a75cfc16721937272ed29462a750b60c8
  10. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e
  11. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c7874dad84b20433c0fe3919f291a762d40de08b
  12. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d306da8833e75f669d93424fd84940236f3850bc
  13. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <5.10.261; version=0 <5.15.212; version=0 <6.1.178; version=0 <6.12.97; version=0 <6.18.40; version=0 <6.6.145; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <22ec7a9fe9153d2737ee9b2fa6d2e43a1491decf; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2ed3c9d955e8cd6361f130623baa664a75fb345f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4606467a75cfc16721937272ed29462a750b60c8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ba35b1c674ca3841c0dfadd698f2c1b3ec542d4e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c7874dad84b20433c0fe3919f291a762d40de08b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d306da8833e75f669d93424fd84940236f3850bc; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e602c93b25bda4a9d0ff1791a4bdbfdcbb074af1

Published CVSS scores

7.5Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.0Red HatCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
9.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-911Improper Update of Reference Count
T1190Exploit Public-Facing Application

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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