CVE-2026-23276

Kernel crash via unbounded tunnel recursion

Published Mar 20, 2026 · Updated Mar 20, 2026

Uncontrolled recursion in Linux Kernel tunnel transmission allows local users to crash the kernel through a crafted network configuration. The iptunnel_xmit and ip6tunnel_xmit paths omit a tunnel-specific recursion guard, so broadcast traffic can loop between a broadcast bond and GRE tap slaves until the kernel stack overflows. Exploitation requires control of a bond in broadcast mode with GRE tap slaves whose tunnels route back through that bond; the reported consequence is a kernel crash.

CVSS severity5.5
Medium
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled recursion in Linux Kernel tunnel transmission allows local users to crash the kernel through a crafted network configuration. The iptunnel_xmit and ip6tunnel_xmit paths omit a tunnel-specific recursion guard, so broadcast traffic can loop between a broadcast bond and GRE tap slaves until the kernel stack overflows. Exploitation requires control of a bond in broadcast mode with GRE tap slaves whose tunnels route back through that bond; the reported consequence is a kernel crash.

The record

CVE
CVE-2026-23276
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-674, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 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=2.6.37
  2. Affected versionversion=3f266b04185de51d8e6446eb1fccec3b5e7ce575
  3. Affected versionversion=745e20f1b626b1be4b100af5d4bf7b3439392f8f <6f1a9140ecda3baba3d945b9a6155af4268aafc4
  4. Affected versionversion=745e20f1b626b1be4b100af5d4bf7b3439392f8f <8a57deeb256069f262957d8012418559ff66c385
  5. Affected versionversion=745e20f1b626b1be4b100af5d4bf7b3439392f8f <b56b8d19bd05e2a8338385c770bc2b60590bc81e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.37; version=3f266b04185de51d8e6446eb1fccec3b5e7ce575; version=745e20f1b626b1be4b100af5d4bf7b3439392f8f <6f1a9140ecda3baba3d945b9a6155af4268aafc4; version=745e20f1b626b1be4b100af5d4bf7b3439392f8f <8a57deeb256069f262957d8012418559ff66c385; version=745e20f1b626b1be4b100af5d4bf7b3439392f8f <b56b8d19bd05e2a8338385c770bc2b60590bc81e

Published CVSS scores

5.5NIST NVDCVSS: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

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-674Uncontrolled Recursion
T1499.004Application or System Exploitation

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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