CVE-2026-64535Network attack vector

Kernel memory corruption via double reference release

Published Jul 27, 2026 · Updated Jul 27, 2026

Use-after-free in the nvmet-tcp target in Linux Kernel allows remote attackers to corrupt kernel memory via a malformed data digest. The digest-error path calls nvmet_req_uninit() without marking the command complete, so queue teardown calls it again and performs a second percpu_ref_put() against one reference. Reachability requires data digest on an NVMe/TCP connection, a mismatching non-final H2C_DATA PDU, and an R2T-based transfer; the stale queue reference permits a kernel crash or further memory corruption.

CVSS severity9.8
Critical
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the nvmet-tcp target in Linux Kernel allows remote attackers to corrupt kernel memory via a malformed data digest. The digest-error path calls nvmet_req_uninit() without marking the command complete, so queue teardown calls it again and performs a second percpu_ref_put() against one reference. Reachability requires data digest on an NVMe/TCP connection, a mismatching non-final H2C_DATA PDU, and an R2T-based transfer; the stale queue reference permits a kernel crash or further memory corruption.

The record

CVE
CVE-2026-64535
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, 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 <6.1.178
  2. Affected versionversion=0 <6.12.97
  3. Affected versionversion=0 <6.18.40
  4. Affected versionversion=0 <6.6.145
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <088ee46c18d99baef453afd74181dd40ade044ad
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6f9442983a3e4227afd1c83a5251ddbca585ea21
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <96fe2513df590e74b04253a45089cae75569570e
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dbbd07d0a7020b80f6a7028e561908f7b83b3d5a
  9. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e091ff83d962f9ed00d9bd70443676de9fe98bdc

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=0 <6.1.178; version=0 <6.12.97; version=0 <6.18.40; version=0 <6.6.145; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <088ee46c18d99baef453afd74181dd40ade044ad; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <6f9442983a3e4227afd1c83a5251ddbca585ea21; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <96fe2513df590e74b04253a45089cae75569570e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dbbd07d0a7020b80f6a7028e561908f7b83b3d5a; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <e091ff83d962f9ed00d9bd70443676de9fe98bdc

Published CVSS scores

9.8Linux 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 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-416Use After Free
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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