FKIE_CVE-2026-23003
Vulnerability from fkie_nvd - Published: 2026-01-25 15:15 - Updated: 2026-01-26 15:03
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv()
Blamed commit did not take care of VLAN encapsulations
as spotted by syzbot [1].
Use skb_vlan_inet_prepare() instead of pskb_inet_may_pull().
[1]
BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x7a8/0x1fa0 include/net/inet_ecn.h:321
__INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]
INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]
IP6_ECN_decapsulate+0x7a8/0x1fa0 include/net/inet_ecn.h:321
ip6ip6_dscp_ecn_decapsulate+0x16f/0x1b0 net/ipv6/ip6_tunnel.c:729
__ip6_tnl_rcv+0xed9/0x1b50 net/ipv6/ip6_tunnel.c:860
ip6_tnl_rcv+0xc3/0x100 net/ipv6/ip6_tunnel.c:903
gre_rcv+0x1529/0x1b90 net/ipv6/ip6_gre.c:-1
ip6_protocol_deliver_rcu+0x1c89/0x2c60 net/ipv6/ip6_input.c:438
ip6_input_finish+0x1f4/0x4a0 net/ipv6/ip6_input.c:489
NF_HOOK include/linux/netfilter.h:318 [inline]
ip6_input+0x9c/0x330 net/ipv6/ip6_input.c:500
ip6_mc_input+0x7ca/0xc10 net/ipv6/ip6_input.c:590
dst_input include/net/dst.h:474 [inline]
ip6_rcv_finish+0x958/0x990 net/ipv6/ip6_input.c:79
NF_HOOK include/linux/netfilter.h:318 [inline]
ipv6_rcv+0xf1/0x3c0 net/ipv6/ip6_input.c:311
__netif_receive_skb_one_core net/core/dev.c:6139 [inline]
__netif_receive_skb+0x1df/0xac0 net/core/dev.c:6252
netif_receive_skb_internal net/core/dev.c:6338 [inline]
netif_receive_skb+0x57/0x630 net/core/dev.c:6397
tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485
tun_get_user+0x5c0e/0x6c60 drivers/net/tun.c:1953
tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0xbe2/0x15d0 fs/read_write.c:686
ksys_write fs/read_write.c:738 [inline]
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746
x64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was created at:
slab_post_alloc_hook mm/slub.c:4960 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_node_noprof+0x9e7/0x17a0 mm/slub.c:5315
kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:586
__alloc_skb+0x805/0x1040 net/core/skbuff.c:690
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6712
sock_alloc_send_pskb+0xacc/0xc60 net/core/sock.c:2995
tun_alloc_skb drivers/net/tun.c:1461 [inline]
tun_get_user+0x1142/0x6c60 drivers/net/tun.c:1794
tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0xbe2/0x15d0 fs/read_write.c:686
ksys_write fs/read_write.c:738 [inline]
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x1fb/0x4d0 fs/read_write.c:746
x64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
CPU: 0 UID: 0 PID: 6465 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv()\n\nBlamed commit did not take care of VLAN encapsulations\nas spotted by syzbot [1].\n\nUse skb_vlan_inet_prepare() instead of pskb_inet_may_pull().\n\n[1]\n BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\n BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n BUG: 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]\n INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n IP6_ECN_decapsulate+0x7a8/0x1fa0 include/net/inet_ecn.h:321\n ip6ip6_dscp_ecn_decapsulate+0x16f/0x1b0 net/ipv6/ip6_tunnel.c:729\n __ip6_tnl_rcv+0xed9/0x1b50 net/ipv6/ip6_tunnel.c:860\n ip6_tnl_rcv+0xc3/0x100 net/ipv6/ip6_tunnel.c:903\n gre_rcv+0x1529/0x1b90 net/ipv6/ip6_gre.c:-1\n ip6_protocol_deliver_rcu+0x1c89/0x2c60 net/ipv6/ip6_input.c:438\n ip6_input_finish+0x1f4/0x4a0 net/ipv6/ip6_input.c:489\n NF_HOOK include/linux/netfilter.h:318 [inline]\n ip6_input+0x9c/0x330 net/ipv6/ip6_input.c:500\n ip6_mc_input+0x7ca/0xc10 net/ipv6/ip6_input.c:590\n dst_input include/net/dst.h:474 [inline]\n ip6_rcv_finish+0x958/0x990 net/ipv6/ip6_input.c:79\n NF_HOOK include/linux/netfilter.h:318 [inline]\n ipv6_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\n netif_receive_skb_internal net/core/dev.c:6338 [inline]\n netif_receive_skb+0x57/0x630 net/core/dev.c:6397\n tun_rx_batched+0x1df/0x980 drivers/net/tun.c:1485\n tun_get_user+0x5c0e/0x6c60 drivers/net/tun.c:1953\n tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999\n new_sync_write fs/read_write.c:593 [inline]\n vfs_write+0xbe2/0x15d0 fs/read_write.c:686\n ksys_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\n x64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nUninit was created at:\n slab_post_alloc_hook mm/slub.c:4960 [inline]\n slab_alloc_node mm/slub.c:5263 [inline]\n kmem_cache_alloc_node_noprof+0x9e7/0x17a0 mm/slub.c:5315\n kmalloc_reserve+0x13c/0x4b0 net/core/skbuff.c:586\n __alloc_skb+0x805/0x1040 net/core/skbuff.c:690\n alloc_skb include/linux/skbuff.h:1383 [inline]\n alloc_skb_with_frags+0xc5/0xa60 net/core/skbuff.c:6712\n sock_alloc_send_pskb+0xacc/0xc60 net/core/sock.c:2995\n tun_alloc_skb drivers/net/tun.c:1461 [inline]\n tun_get_user+0x1142/0x6c60 drivers/net/tun.c:1794\n tun_chr_write_iter+0x3e9/0x5c0 drivers/net/tun.c:1999\n new_sync_write fs/read_write.c:593 [inline]\n vfs_write+0xbe2/0x15d0 fs/read_write.c:686\n ksys_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\n x64_sys_call+0x30ab/0x3e70 arch/x86/include/generated/asm/syscalls_64.h:2\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xd3/0xf80 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\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"
}
],
"id": "CVE-2026-23003",
"lastModified": "2026-01-26T15:03:33.357",
"metrics": {},
"published": "2026-01-25T15:15:55.170",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/81c734dae203757fb3c9eee6f9896386940776bd"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b9f915340f25cae1562f18e1eb52deafca328414"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/df5ffde9669314500809bc498ae73d6d3d9519ac"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
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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