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Vulnerability · Published Mar 27, 2025 · Assigned by Linux

CVE-2023-53020l2tp: close all race conditions in l2tp_tunnel_register()

Medium 4.7

In plain English

A medium-severity race condition in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.7Medium
Exploit odds (30 days)0.1%top 96.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: l2tp: close all race conditions in l2tp_tunnel_register() The code in l2tp_tunnel_register() is racy in several ways: 1. It modifies the tunnel socket _after_ publishing it. 2. It calls setup_udp_tunnel_sock() on an existing socket without locking. 3. It changes sock lock class on fly, which triggers many syzbot reports. This patch amends all of them by moving socket initialization code before publishing and under sock lock. As suggested by Jakub, the l2tp lockdep class is not necessary as we can just switch to bh_lock_sock_nested().

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.11-1DEBIAN-CVE-2023-53020
Debian:13linux6.1.11-1DEBIAN-CVE-2023-53020
Debian:14linux6.1.11-1DEBIAN-CVE-2023-53020
Ubuntu:22.04:LTSlinux5.15.0-70.77UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-aws5.15.0-1034.38UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure5.15.0-1036.43UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-fde5.15.0-1036.43.1UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gcp5.15.0-1032.40UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gke5.15.0-1031.36UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-gkeop5.15.0-1018.23UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-ibm5.15.0-1028.31UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-intel-iotg5.15.0-1028.33UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-kvm5.15.0-1031.36UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-lowlatency5.15.0-70.77UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-nvidia5.15.0-1023.23UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oracle5.15.0-1033.39UBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-raspi5.15.0-1027.29UBUNTU-CVE-2023-53020
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2023-53020
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2023-53020
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2023-53020

Affected products (as reported)

VendorProductVersions
Linux Linux 37159ef2c1ae1e696b24b260b241209a19f92c60 – before 2d77e5c0ad79004b5ef901895437e9cce6dfcc7e37159ef2c1ae1e696b24b260b241209a19f92c60 – before 77e8ed776cdb1a24b2aab8fe7c6f1f154235e1ce37159ef2c1ae1e696b24b260b241209a19f92c60 – before cef0845b6dcfa2f6c2c832e7f9622551456c741d37159ef2c1ae1e696b24b260b241209a19f92c60 – before 0b2c59720e65885a394a017d0cf9cab118914682
Linux Linux 3.6

Weakness: CWE-362 · Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

References