CVE-2026-23439udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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
- 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before dfc96ae0074cc47b5478a59e5aa19233e434243f; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before 66117dbb3dbae82f86735bf727b1d59cc677afa1; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before ba7c9ddcdd077942b798979edb035207374d4096; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before a05a2149386f6dfb4245f522acdbef892acafc84; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before 9f036aa0fe46c19e938f03d10e02c23f4fffae5e; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before 003343985f26dfefd0c94b1fe1316a2de74428b9; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before 12aa4b73a67d95bc739995a2d6943aec2f9785c9; from fd384412e199b62c3ddaabd18dce86d0e164c5b9 before b3a6df291fecf5f8a308953b65ca72b7fc9e015d | CNA record |
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name) | from V3.1.6 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 3.18.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.78; from 6.13 before 6.18.20; from 6.19 before 6.19.10; 3.18; and 7 more ranges | NVD |
References
- https://git.kernel.org/stable/c/dfc96ae0074cc47b5478a59e5aa19233e434243fpatch
- https://git.kernel.org/stable/c/66117dbb3dbae82f86735bf727b1d59cc677afa1patch
- https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096patch
- https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84patch
- https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5epatch
- https://git.kernel.org/stable/c/003343985f26dfefd0c94b1fe1316a2de74428b9patch
- https://git.kernel.org/stable/c/12aa4b73a67d95bc739995a2d6943aec2f9785c9patch
- https://git.kernel.org/stable/c/b3a6df291fecf5f8a308953b65ca72b7fc9e015dpatch
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.