CVE-2026-23439 (GCVE-0-2026-23439)
Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-04-18 08:58
VLAI?
Title
udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n
Summary
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < dfc96ae0074cc47b5478a59e5aa19233e434243f
(git)
Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < 66117dbb3dbae82f86735bf727b1d59cc677afa1 (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < ba7c9ddcdd077942b798979edb035207374d4096 (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < a05a2149386f6dfb4245f522acdbef892acafc84 (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < 9f036aa0fe46c19e938f03d10e02c23f4fffae5e (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < 003343985f26dfefd0c94b1fe1316a2de74428b9 (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < 12aa4b73a67d95bc739995a2d6943aec2f9785c9 (git) Affected: fd384412e199b62c3ddaabd18dce86d0e164c5b9 , < b3a6df291fecf5f8a308953b65ca72b7fc9e015d (git) |
|||||||
|
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n\n\nWhen CONFIG_IPV6 is disabled, the udp_sock_create6() function returns 0\n(success) without actually creating a socket. Callers such as\nfou_create() then proceed to dereference the uninitialized socket\npointer, resulting in a NULL pointer dereference.\n\nThe captured NULL deref crash:\n BUG: kernel NULL pointer dereference, address: 0000000000000018\n RIP: 0010:fou_nl_add_doit (net/ipv4/fou_core.c:590 net/ipv4/fou_core.c:764)\n [...]\n Call Trace:\n \u003cTASK\u003e\n genl_family_rcv_msg_doit.constprop.0 (net/netlink/genetlink.c:1114)\n genl_rcv_msg (net/netlink/genetlink.c:1194 net/netlink/genetlink.c:1209)\n [...]\n netlink_rcv_skb (net/netlink/af_netlink.c:2550)\n genl_rcv (net/netlink/genetlink.c:1219)\n netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\n netlink_sendmsg (net/netlink/af_netlink.c:1894)\n __sock_sendmsg (net/socket.c:727 (discriminator 1) net/socket.c:742 (discriminator 1))\n __sys_sendto (./include/linux/file.h:62 (discriminator 1) ./include/linux/file.h:83 (discriminator 1) net/socket.c:2183 (discriminator 1))\n __x64_sys_sendto (net/socket.c:2213 (discriminator 1) net/socket.c:2209 (discriminator 1) net/socket.c:2209 (discriminator 1))\n do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))\n entry_SYSCALL_64_after_hwframe (net/arch/x86/entry/entry_64.S:130)\n\nThis patch makes udp_sock_create6 return -EPFNOSUPPORT instead, so\ncallers correctly take their error paths. There is only one caller of\nthe vulnerable function and only privileged users can trigger it."
}
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Callers such as\\nfou_create() then proceed to dereference the uninitialized socket\\npointer, resulting in a NULL pointer dereference.\\n\\nThe captured NULL deref crash:\\n BUG: kernel NULL pointer dereference, address: 0000000000000018\\n RIP: 0010:fou_nl_add_doit (net/ipv4/fou_core.c:590 net/ipv4/fou_core.c:764)\\n [...]\\n Call Trace:\\n \u003cTASK\u003e\\n genl_family_rcv_msg_doit.constprop.0 (net/netlink/genetlink.c:1114)\\n genl_rcv_msg (net/netlink/genetlink.c:1194 net/netlink/genetlink.c:1209)\\n [...]\\n netlink_rcv_skb (net/netlink/af_netlink.c:2550)\\n genl_rcv (net/netlink/genetlink.c:1219)\\n netlink_unicast (net/netlink/af_netlink.c:1319 net/netlink/af_netlink.c:1344)\\n netlink_sendmsg (net/netlink/af_netlink.c:1894)\\n __sock_sendmsg (net/socket.c:727 (discriminator 1) net/socket.c:742 (discriminator 1))\\n __sys_sendto (./include/linux/file.h:62 (discriminator 1) ./include/linux/file.h:83 (discriminator 1) net/socket.c:2183 (discriminator 1))\\n __x64_sys_sendto (net/socket.c:2213 (discriminator 1) net/socket.c:2209 (discriminator 1) net/socket.c:2209 (discriminator 1))\\n do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))\\n entry_SYSCALL_64_after_hwframe (net/arch/x86/entry/entry_64.S:130)\\n\\nThis patch makes udp_sock_create6 return -EPFNOSUPPORT instead, so\\ncallers correctly take their error paths. 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}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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