CVE-2026-23439 (GCVE-0-2026-23439)
Vulnerability from cvelistv5
Published
2026-04-03 15:15
Modified
2026-04-18 08:58
Severity ?
VLAI Severity ?
EPSS score ?
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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 Version: fd384412e199b62c3ddaabd18dce86d0e164c5b9 |
||
{
"containers": {
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"product": "Linux",
"programFiles": [
"include/net/udp_tunnel.h"
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},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.253",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.203",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.167",
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},
{
"lessThanOrEqual": "6.6.*",
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"version": "6.6.130",
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{
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"status": "unaffected",
"version": "6.12.78",
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},
{
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},
{
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},
{
"lessThanOrEqual": "*",
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"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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}
],
"negate": false,
"operator": "OR"
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],
"descriptions": [
{
"lang": "en",
"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."
}
],
"providerMetadata": {
"dateUpdated": "2026-04-18T08:58:55.464Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/dfc96ae0074cc47b5478a59e5aa19233e434243f"
},
{
"url": "https://git.kernel.org/stable/c/66117dbb3dbae82f86735bf727b1d59cc677afa1"
},
{
"url": "https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096"
},
{
"url": "https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84"
},
{
"url": "https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5e"
},
{
"url": "https://git.kernel.org/stable/c/003343985f26dfefd0c94b1fe1316a2de74428b9"
},
{
"url": "https://git.kernel.org/stable/c/12aa4b73a67d95bc739995a2d6943aec2f9785c9"
},
{
"url": "https://git.kernel.org/stable/c/b3a6df291fecf5f8a308953b65ca72b7fc9e015d"
}
],
"title": "udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-23439",
"datePublished": "2026-04-03T15:15:23.734Z",
"dateReserved": "2026-01-13T15:37:46.017Z",
"dateUpdated": "2026-04-18T08:58:55.464Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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