{"id":"CVE-2026-23439","state":"PUBLISHED","title":"udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n","description":"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    <TASK>\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.","publishedAt":"2026-04-03T15:15:23.734Z","updatedAt":"2026-10-15T01:15:01.223Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"dfc96ae0074cc47b5478a59e5aa19233e434243f","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"66117dbb3dbae82f86735bf727b1d59cc677afa1","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"ba7c9ddcdd077942b798979edb035207374d4096","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"a05a2149386f6dfb4245f522acdbef892acafc84","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"9f036aa0fe46c19e938f03d10e02c23f4fffae5e","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"003343985f26dfefd0c94b1fe1316a2de74428b9","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"12aa4b73a67d95bc739995a2d6943aec2f9785c9","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"b3a6df291fecf5f8a308953b65ca72b7fc9e015d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/udp_tunnel.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.18","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.20","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.10","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/udp_tunnel.h"]}],"references":["https://git.kernel.org/stable/c/dfc96ae0074cc47b5478a59e5aa19233e434243f","https://git.kernel.org/stable/c/66117dbb3dbae82f86735bf727b1d59cc677afa1","https://git.kernel.org/stable/c/ba7c9ddcdd077942b798979edb035207374d4096","https://git.kernel.org/stable/c/a05a2149386f6dfb4245f522acdbef892acafc84","https://git.kernel.org/stable/c/9f036aa0fe46c19e938f03d10e02c23f4fffae5e","https://git.kernel.org/stable/c/003343985f26dfefd0c94b1fe1316a2de74428b9","https://git.kernel.org/stable/c/12aa4b73a67d95bc739995a2d6943aec2f9785c9","https://git.kernel.org/stable/c/b3a6df291fecf5f8a308953b65ca72b7fc9e015d","https://cert-portal.siemens.com/productcert/html/ssa-082556.html","https://cert-portal.siemens.com/productcert/html/ssa-019113.html","https://cert-portal.siemens.com/productcert/html/ssa-457936.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:21.040Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/23xxx/CVE-2026-23439.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-23439","state":"PUBLISHED","datePublished":"2026-04-03T15:15:23.734Z","dateUpdated":"2026-10-15T01:15:01.223Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-01-13T15:37:46.017Z"},"containers":{"cna":{"title":"udp_tunnel: fix NULL deref caused by udp_sock_create6 when CONFIG_IPV6=n","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    <TASK>\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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"dfc96ae0074cc47b5478a59e5aa19233e434243f","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"66117dbb3dbae82f86735bf727b1d59cc677afa1","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"ba7c9ddcdd077942b798979edb035207374d4096","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"a05a2149386f6dfb4245f522acdbef892acafc84","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"9f036aa0fe46c19e938f03d10e02c23f4fffae5e","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"003343985f26dfefd0c94b1fe1316a2de74428b9","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"12aa4b73a67d95bc739995a2d6943aec2f9785c9","versionType":"git"},{"version":"fd384412e199b62c3ddaabd18dce86d0e164c5b9","status":"affected","lessThan":"b3a6df291fecf5f8a308953b65ca72b7fc9e015d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/udp_tunnel.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.18","versionType":"semver"},{"version":"5.10.253","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.203","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.167","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.130","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.78","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.20","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.10","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/net/udp_tunnel.h"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:06:55.791Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"6.1.167"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"6.6.130"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"6.12.78"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"6.18.20"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"6.19.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.18","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"affected":[{"vendor":"Siemens","product":"SIMATIC 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