CVE-2026-31684

Local kernel crash via truncated nested VLAN header

Published Apr 25, 2026 · Updated Apr 25, 2026

Out-of-bounds read in affected Linux Kernel releases allows local users to crash the kernel via a partially linearized nested VLAN packet. The tcf_csum_act() path reads h_vlan_encapsulated_proto and pulls VLAN_HLEN from skb->data without first ensuring that the complete inner header is linear. Exploitation requires low-privileged local access and an act_csum traffic-control action processing the crafted packet; the reported consequence is loss of system availability.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in affected Linux Kernel releases allows local users to crash the kernel via a partially linearized nested VLAN packet. The tcf_csum_act() path reads h_vlan_encapsulated_proto and pulls VLAN_HLEN from skb->data without first ensuring that the complete inner header is linear. Exploitation requires low-privileged local access and an act_csum traffic-control action processing the crafted packet; the reported consequence is loss of system availability.

The record

CVE
CVE-2026-31684
Published
Apr 25, 2026
Updated
Apr 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 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=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <3d165d975305cf76ff0b10a3c798fb31e5f5f9a5
  2. Affected versionversion=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <a69738efea0996d05a3c7d2178551b891744df1b
  3. Affected versionversion=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <c842743d073bdd683606cb414eb0ca84465dd834
  4. Affected versionversion=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <ec4930979b3f7bbeb7af5744599fc6603a4dba62
  5. Affected versionversion=3764bfae5056e95617b6ee074129297e11710886
  6. Affected versionversion=5.1

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <3d165d975305cf76ff0b10a3c798fb31e5f5f9a5; version=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <a69738efea0996d05a3c7d2178551b891744df1b; version=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <c842743d073bdd683606cb414eb0ca84465dd834; version=2ecba2d1e45b24620a7c3df9531895cf68d5dec6 <ec4930979b3f7bbeb7af5744599fc6603a4dba62; version=3764bfae5056e95617b6ee074129297e11710886; version=5.1

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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