CVE-2023-3812

Local privilege escalation via oversized TUN packet

Published Jul 24, 2023 · Updated Feb 26, 2026

Out-of-bounds write in the Linux kernel TUN/TAP driver in affected Red Hat Enterprise Linux releases allows local users to crash the host. With NAPI fragments enabled, tun_napi_alloc_frags fails to reject packet lengths above the Ethernet MTU allocation limit before building the socket buffer. A local user able to write an oversized IPv6 packet to a TUN/TAP device can corrupt kernel memory, causing a crash or privilege escalation.

CVSS severity7.8
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

Out-of-bounds write in the Linux kernel TUN/TAP driver in affected Red Hat Enterprise Linux releases allows local users to crash the host. With NAPI fragments enabled, tun_napi_alloc_frags fails to reject packet lengths above the Ethernet MTU allocation limit before building the socket buffer. A local user able to write an oversized IPv6 packet to a TUN/TAP device can corrupt kernel memory, causing a crash or privilege escalation.

The record

CVE
CVE-2023-3812
Published
Jul 24, 2023
Updated
Feb 26, 2026
Vendor
Red Hat
Product
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
Classifications
CWE-787, T1499, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 24, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 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?

Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Advanced Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Telecommunications Update ServiceAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.2 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.4 Telecommunications Update ServiceAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.8 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.6 Extended Update SupportAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.1 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat Enterprise Linux 8.4 Update Services for SAP SolutionsAffected versions are unavailable in this record.
Red Hat · Red Hat Virtualization 4 for Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

7.8Red Hat, Inc.CVSS:3.1/AV:L/AC:L/PR:L/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 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

CWE-787Out-of-bounds Write
T1499Endpoint Denial of Service
T1068Exploitation for Privilege Escalation

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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