CVE-2026-64522Network attack vector

Kernel compromise via IPsec mode-block counter underflow

Published Jul 25, 2026 · Updated Jul 25, 2026

Integer underflow in the Linux Kernel mlx5e IPsec path allows remote attackers to corrupt kernel state via an acquire SA. The mlx5e_xfrm_add_state() acquire-flow path skips mlx5_eswitch_block_mode() but reaches a common success label that still calls mlx5_eswitch_unblock_mode(), wrapping esw->offloads.num_block_mode. The flaw requires mlx5 IPsec offload and creation of a temporary acquire SA; kernel.org assesses possible data exposure, kernel-state modification, and service interruption.

CVSS severity8.8
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in the Linux Kernel mlx5e IPsec path allows remote attackers to corrupt kernel state via an acquire SA. The mlx5e_xfrm_add_state() acquire-flow path skips mlx5_eswitch_block_mode() but reaches a common success label that still calls mlx5_eswitch_unblock_mode(), wrapping esw->offloads.num_block_mode. The flaw requires mlx5 IPsec offload and creation of a temporary acquire SA; kernel.org assesses possible data exposure, kernel-state modification, and service interruption.

The record

CVE
CVE-2026-64522
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-191
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 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=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <abe003b33223ff33552f291644bf35d9c2f992fb
  2. Affected versionversion=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <b5bd4249e430f5963d559708ee96a671716d2400
  3. Affected versionversion=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <ecafd8284e527666e83261e6e57a7c7341d591cb
  4. Affected versionversion=6.17.4 <6.18
  5. Affected versionversion=6.18
  6. Affected versionversion=993c4ba71596c30418ba5a0ddcf4f9c2f431466a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <abe003b33223ff33552f291644bf35d9c2f992fb; version=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <b5bd4249e430f5963d559708ee96a671716d2400; version=22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 <ecafd8284e527666e83261e6e57a7c7341d591cb; version=6.17.4 <6.18; version=6.18; version=993c4ba71596c30418ba5a0ddcf4f9c2f431466a

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-191Integer Underflow (Wrap or Wraparound)

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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