CVE-2026-23439

MEDIUM EPSS 2.4%

Published Apr 3, 20262mo ago · Modified Jun 17, 20261w ago

5.5 CVSS 3.1

Medium

Published Apr 3, 2026 2mo ago

Last Modified Jun 17, 2026 1w ago

Description

In the Linux kernel, the following vulnerability has been resolved: udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n When CONFIG_IPV6 is disabled, the udp_sock_create6() function returns 0 (success) without actually creating a socket. Callers such as fou_create() then proceed to dereference the uninitialized socket pointer, resulting in a NULL pointer dereference. The captured NULL deref crash: BUG: kernel NULL pointer dereference, address: 0000000000000018 RIP: 0010:fou_nl_add_doit (net/ipv4/fou_core.c:590 net/ipv4/fou_core.c:764) [...] Call Trace: <TASK> genl_family_rcv_msg_doit.constprop.0 (net/netlink/genetlink.c:1114) genl_rcv_msg (net/netlink/genetlink.c:1194 net/netlink/genetlink.c:1209) [...] netlink_rcv_skb (net/netlink/af_netlink.c:2550) genl_rcv (net/netlink/genetlink.c:1219) netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344) netlink_sendmsg (net/netlink/af_netlink.c:1894) __sock_sendmsg (net/socket.c:727 (discriminator 1) net/socket.c:742 (discriminator 1)) __sys_sendto (./include/linux/file.h:62 (discriminator 1) ./include/linux/file.h:83 (discriminator 1) net/socket.c:2183 (discriminator 1)) __x64_sys_sendto (net/socket.c:2213 (discriminator 1) net/socket.c:2209 (discriminator 1) net/socket.c:2209 (discriminator 1)) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (net/arch/x86/entry/entry_64.S:130) This patch makes udp_sock_create6 return -EPFNOSUPPORT instead, so callers correctly take their error paths. There is only one caller of the vulnerable function and only privileged users can trigger it.

CVSS Details

Base Score

5.5

Exploitability

1.8

Impact

3.6

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector Local

Attack Complexity Low

Privileges Required Low

User Interaction None

Scope Unchanged

Confidentiality None

Integrity None

Availability High

Threat Intelligence

EPSS Exploit Probability

2.4% percentile

Exploit & Patch Status

No Known Exploit

Patch Available

Weaknesses 1

CWE-476 NULL Pointer Dereference Memory Safety

Affected Products 15

Vendor	Product	Version	Range
linux	linux_kernel	*	≥3.18.1 – <5.10.253
linux	linux_kernel	*	≥5.11 – <5.15.203
linux	linux_kernel	*	≥5.16 – <6.1.167
linux	linux_kernel	*	≥6.2 – <6.6.130
linux	linux_kernel	*	≥6.7 – <6.12.78
linux	linux_kernel	*	≥6.13 – <6.18.20
linux	linux_kernel	*	≥6.19 – <6.19.10
linux	linux_kernel	3.18	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any
linux	linux_kernel	7.0	any

References 8

git.kernel.org https://git.kernel.org/stable/c/003343985f26dfefd0c94b1fe1316a2de74428b9

Patch
git.kernel.org https://git.kernel.org/stable/c/12aa4b73a67d95bc739995a2d6943aec2f9785c9

Patch
git.kernel.org https://git.kernel.org/stable/c/66117dbb3dbae82f86735bf727b1d59cc677afa1

Patch
git.kernel.org https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5e

Patch
git.kernel.org https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84

Patch
git.kernel.org https://git.kernel.org/stable/c/b3a6df291fecf5f8a308953b65ca72b7fc9e015d

Patch
git.kernel.org https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096

Patch
git.kernel.org https://git.kernel.org/stable/c/dfc96ae0074cc47b5478a59e5aa19233e434243f

Patch

Remediation

git.kernel.org https://git.kernel.org/stable/c/003343985f26dfefd0c94b1fe1316a2de74428b9

Patch
git.kernel.org https://git.kernel.org/stable/c/12aa4b73a67d95bc739995a2d6943aec2f9785c9

Patch
git.kernel.org https://git.kernel.org/stable/c/66117dbb3dbae82f86735bf727b1d59cc677afa1

Patch
git.kernel.org https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5e

Patch
git.kernel.org https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84

Patch
git.kernel.org https://git.kernel.org/stable/c/b3a6df291fecf5f8a308953b65ca72b7fc9e015d

Patch
git.kernel.org https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096

Patch
git.kernel.org https://git.kernel.org/stable/c/dfc96ae0074cc47b5478a59e5aa19233e434243f

Patch