CVE-2023-53020

Local system crash via L2TP socket race

Published Mar 27, 2025 · Updated May 11, 2026

Race condition in the Linux kernel allows local users to crash the system through concurrent L2TP tunnel creation. The l2tp_tunnel_register() path publishes a tunnel socket before completing initialization, invokes setup_udp_tunnel_sock() on an existing socket without its lock, and changes the socket lock class while live. Exploitation requires local low-privilege access and a race; successful triggering disrupts availability without reported confidentiality or integrity impact.

CVSS severity4.7
Medium
EPSS probability0.14%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in the Linux kernel allows local users to crash the system through concurrent L2TP tunnel creation. The l2tp_tunnel_register() path publishes a tunnel socket before completing initialization, invokes setup_udp_tunnel_sock() on an existing socket without its lock, and changes the socket lock class while live. Exploitation requires local low-privilege access and a race; successful triggering disrupts availability without reported confidentiality or integrity impact.

The record

CVE
CVE-2023-53020
Published
Mar 27, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-362, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 27, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=3.6
  2. Affected versionversion=37159ef2c1ae1e696b24b260b241209a19f92c60 <0b2c59720e65885a394a017d0cf9cab118914682
  3. Affected versionversion=37159ef2c1ae1e696b24b260b241209a19f92c60 <2d77e5c0ad79004b5ef901895437e9cce6dfcc7e
  4. Affected versionversion=37159ef2c1ae1e696b24b260b241209a19f92c60 <77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce
  5. Affected versionversion=37159ef2c1ae1e696b24b260b241209a19f92c60 <cef0845b6dcfa2f6c2c832e7f9622551456c741d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.6; version=37159ef2c1ae1e696b24b260b241209a19f92c60 <0b2c59720e65885a394a017d0cf9cab118914682; version=37159ef2c1ae1e696b24b260b241209a19f92c60 <2d77e5c0ad79004b5ef901895437e9cce6dfcc7e; version=37159ef2c1ae1e696b24b260b241209a19f92c60 <77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce; version=37159ef2c1ae1e696b24b260b241209a19f92c60 <cef0845b6dcfa2f6c2c832e7f9622551456c741d

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7CISACVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7NVDCVSS:3.1/AV:L/AC:H/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 11, 2026Sep 17, 2026
Latest reporting daySep 17, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
T1499Endpoint Denial of Service

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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