{
  "threat_severity" : "Moderate",
  "public_date" : "2026-01-25T00:00:00Z",
  "bugzilla" : {
    "description" : "kernel: ip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv()",
    "id" : "2432681",
    "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2432681"
  },
  "cvss3" : {
    "cvss3_base_score" : "6.1",
    "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:H",
    "status" : "verified"
  },
  "cwe" : "CWE-457",
  "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv()\nBlamed commit did not take care of VLAN encapsulations\nas spotted by syzbot [1].\nUse skb_vlan_inet_prepare() instead of pskb_inet_may_pull().\n[1]\nBUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\nBUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\nBUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x7a8/0x1fa0 include/net/inet_ecn.h:321\n__INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\nINET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\nIP6_ECN_decapsulate+0x7a8/0x1fa0 include/net/inet_ecn.h:321\nip6ip6_dscp_ecn_decapsulate+0x16f/0x1b0 net/ipv6/ip6_tunnel.c:729\n__ip6_tnl_rcv+0xed9/0x1b50 net/ipv6/ip6_tunnel.c:860\nip6_tnl_rcv+0xc3/0x100 net/ipv6/ip6_tunnel.c:903\ngre_rcv+0x1529/0x1b90 net/ipv6/ip6_gre.c:-1\nip6_protocol_deliver_rcu+0x1c89/0x2c60 net/ipv6/ip6_input.c:438\nip6_input_finish+0x1f4/0x4a0 net/ipv6/ip6_input.c:489\nNF_HOOK include/linux/netfilter.h:318 [inline]\nip6_input+0x9c/0x330 net/ipv6/ip6_input.c:500\nip6_mc_input+0x7ca/0xc10 net/ipv6/ip6_input.c:590\ndst_input include/net/dst.h:474 [inline]\nip6_rcv_finish+0x958/0x990 net/ipv6/ip6_input.c:79\nNF_HOOK include/linux/netfilter.h:318 [inline]\nipv6_rcv+0xf1/0x3c0 net/ipv6/ip6_input.c:311\n__netif_receive_skb_one_core net/core/dev.c:6139 [inline]\n__netif_receive_skb+0x1df/0xac0 net/core/dev.c:6252\nnetif_receive_skb_internal net/core/dev.c:6338 [inline]\nnetif_receive_skb+0x57/0x630 net/core/dev.c:6397\ntun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485\ntun_get_user+0x5c0e/0x6c60 drivers/net/tun.c:1953\ntun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999\nnew_sync_write fs/read_write.c:593 [inline]\nvfs_write+0xbe2/0x15d0 fs/read_write.c:686\nksys_write fs/read_write.c:738 [inline]\n__do_sys_write fs/read_write.c:749 [inline]\n__se_sys_write fs/read_write.c:746 [inline]\n__x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746\nx64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2\ndo_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\ndo_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94\nentry_SYSCALL_64_after_hwframe+0x77/0x7f\nUninit was created at:\nslab_post_alloc_hook mm/slub.c:4960 [inline]\nslab_alloc_node mm/slub.c:5263 [inline]\nkmem_cache_alloc_node_noprof+0x9e7/0x17a0 mm/slub.c:5315\nkmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:586\n__alloc_skb+0x805/0x1040 net/core/skbuff.c:690\nalloc_skb include/linux/skbuff.h:1383 [inline]\nalloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6712\nsock_alloc_send_pskb+0xacc/0xc60 net/core/sock.c:2995\ntun_alloc_skb drivers/net/tun.c:1461 [inline]\ntun_get_user+0x1142/0x6c60 drivers/net/tun.c:1794\ntun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999\nnew_sync_write fs/read_write.c:593 [inline]\nvfs_write+0xbe2/0x15d0 fs/read_write.c:686\nksys_write fs/read_write.c:738 [inline]\n__do_sys_write fs/read_write.c:749 [inline]\n__se_sys_write fs/read_write.c:746 [inline]\n__x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746\nx64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2\ndo_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\ndo_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94\nentry_SYSCALL_64_after_hwframe+0x77/0x7f\nCPU: 0 UID: 0 PID: 6465 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025" ],
  "statement" : "The ip6 tunnel receive path could read uninitialized skb data when VLAN encapsulation was present, leading to use of uninitialized values during ECN/DSCP decapsulation. This was detected by KMSAN as an uninitialized memory read in __INET_ECN_decapsulate().",
  "affected_release" : [ {
    "product_name" : "Red Hat Enterprise Linux 10",
    "release_date" : "2026-09-01T00:00:00Z",
    "advisory" : "RHSA-2026:61887",
    "cpe" : "cpe:/o:redhat:enterprise_linux:10.2",
    "package" : "kernel-0:6.12.0-211.50.1.el10_2"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-08-26T00:00:00Z",
    "advisory" : "RHSA-2026:59723",
    "cpe" : "cpe:/a:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-687.42.1.el9_8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "release_date" : "2026-08-26T00:00:00Z",
    "advisory" : "RHSA-2026:59723",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9",
    "package" : "kernel-0:5.14.0-687.42.1.el9_8"
  } ],
  "package_state" : [ {
    "product_name" : "Red Hat Enterprise Linux 6",
    "fix_state" : "Out of support scope",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:6"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 7",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:7"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 8",
    "fix_state" : "Not affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:8"
  }, {
    "product_name" : "Red Hat Enterprise Linux 9",
    "fix_state" : "Affected",
    "package_name" : "kernel-rt",
    "cpe" : "cpe:/o:redhat:enterprise_linux:9"
  } ],
  "references" : [ "https://www.cve.org/CVERecord?id=CVE-2026-23003\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-23003\nhttps://lore.kernel.org/linux-cve-announce/2026012535-CVE-2026-23003-e684@gregkh/T" ],
  "name" : "CVE-2026-23003",
  "csaw" : false
}