CVE-2026-23003
Unknown
Unknown - Not Provided
BaseFortify
Publication date: 2026-01-25
Last updated on: 2026-04-27
Assigner: kernel.org
Description
Description
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
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | 6.8 |
| linux | linux_kernel | From 6.7.4 (inc) to 6.8 (exc) |
| linux | linux_kernel | From 6.13 (inc) to 6.18.7 (exc) |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | 6.19 |
| linux | linux_kernel | From 5.10.210 (inc) to 5.10.249 (exc) |
| linux | linux_kernel | From 5.15.149 (inc) to 5.15.199 (exc) |
| linux | linux_kernel | From 6.1.77 (inc) to 6.1.162 (exc) |
| linux | linux_kernel | From 6.6.16 (inc) to 6.6.122 (exc) |
| linux | linux_kernel | From 6.8.1 (inc) to 6.12.67 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-908 | The product uses or accesses a resource that has not been initialized. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability in the Linux kernel involves the ip6_tunnel component where the code did not properly handle VLAN encapsulations. Specifically, the function __ip6_tnl_rcv() used an incorrect method (pskb_inet_may_pull()) instead of skb_vlan_inet_prepare(), which led to uninitialized values being used during packet processing. This was identified by syzbot and fixed by changing to the correct function to properly prepare VLAN packets.
How can this vulnerability impact me? :
The vulnerability can lead to the use of uninitialized values in the Linux kernel's IPv6 tunneling code, which may cause unpredictable behavior such as kernel crashes or memory corruption. This can affect system stability and security, potentially allowing attackers to exploit the kernel for denial of service or other malicious activities.
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