CVE-2026-64410Network attack vector

Network isolation bypass via unsupported IPIP offload

Published Jul 25, 2026 · Updated Jul 25, 2026

Improper hardware offload in Linux Kernel 6.19 allows remote attackers to bypass IPIP tunnel isolation via forwarded traffic. Netfilter flowtable rule generation omits IPIP outer-match and encapsulation semantics while repeatedly queueing unsupported offload work. Exposure requires a router with an IPIP tunnel and hardware-enabled nftables flowtable; crafted TCP or UDP flows leak or inject traffic, exhaust resources, or blackhole service.

CVSS severity9.8
Critical
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper hardware offload in Linux Kernel 6.19 allows remote attackers to bypass IPIP tunnel isolation via forwarded traffic. Netfilter flowtable rule generation omits IPIP outer-match and encapsulation semantics while repeatedly queueing unsupported offload work. Exposure requires a router with an IPIP tunnel and hardware-enabled nftables flowtable; crafted TCP or UDP flows leak or inject traffic, exhaust resources, or blackhole service.

The record

CVE
CVE-2026-64410
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1190
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

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=6.19
  2. Affected versionversion=ab427db17885814069bae891834f20842f0ac3a4 <6c5dcab95f4cd42a1648739ec9300fbb4b1a021f
  3. Affected versionversion=ab427db17885814069bae891834f20842f0ac3a4 <9efe838c13133acb70c78d04c49e8362fe533566

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.19; version=ab427db17885814069bae891834f20842f0ac3a4 <6c5dcab95f4cd42a1648739ec9300fbb4b1a021f; version=ab427db17885814069bae891834f20842f0ac3a4 <9efe838c13133acb70c78d04c49e8362fe533566

Published CVSS scores

9.8LinuxCVSS: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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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

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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