7.5

CVE-2026-23003: ip6_tunnel: use skb_vlan_inet_prepare() in __ip6_tnl_rcv()

Modified
AliasesUBUNTU-CVE-2026-23003DEBIAN-CVE-2026-23003
Published 25-01-2026Last modified 19-10-2026

Vulnerability summary

CVE-2026-23003 is a high (CVSS 7.5) Use of Uninitialized Resource vulnerability in linux. EPSS estimates a 0.55% chance of exploitation in the next 30 days, higher than 45.9% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 1% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.55%
0%100%
Low · +0.03 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 46 · Related 40
DLA-4475-1DLA-4476-1DSA-6126-1DSA-6127-1OPENSUSE-SU-2026:20416-1RHSA-2026:59723

Timeline

  1. 25-01-2026
    PublishedVulnerability first disclosed.
  2. 19-10-2026
    Last modifiedVulnerability information updated.

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 metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.55%

Chance of exploitation in the next 30 days

Percentile

46%

Versus all other CVEs

30-day change

Increase +0.03 pp

From 0.52% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu155 products
  • linuxAll versions (No fix recorded) | < 5.15.0-176.186 | < 6.8.0-117.117
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-awsAll versions (No fix recorded) | < 5.15.0-1105.112 | < 6.8.0-1055.58
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ a9bc32879a08f23cdb80a48c738017e39aea1080, < f9c5c5b791d3850570796f9e067629474e613796 | ≥ af6b5c50d47ab43e5272ad61935d0ed2e264d3f0, < 64c71d60a21a9ed0a802483dcd422b5b24eb1abe | ≥ d54e4da98bbfa8c257bdca94c49652d81d18a4d8, < 9e1c8c2a33d0a7b1f637b5d0602fe56ed10166af | ≥ 350a6640fac4b53564ec20aa3f4a0922cb0ba5e6, < 2f03dafea0a8096a2eb60f551218b360e5bab9a3 | ≥ 8d975c15c0cd744000ca386247432d57b21f9df0, < df5ffde9669314500809bc498ae73d6d3d9519ac | ≥ 8d975c15c0cd744000ca386247432d57b21f9df0, < b9f915340f25cae1562f18e1eb52deafca328414 | ≥ 8d975c15c0cd744000ca386247432d57b21f9df0, < 81c734dae203757fb3c9eee6f9896386940776bd | c835df3bcc14858ae9b27315dd7de76370b94f3a | ≥ 5.10.210, < 5.10.249 | ≥ 5.15.149, < 5.15.199 | ≥ 6.1.77, < 6.1.162 | ≥ 6.6.16, < 6.6.122 | ≥ 6.7.4, < 6.8 | 6.8
  • linux_kernelEOL≥ 5.10.210, < 5.10.249 | ≥ 5.15.149, < 5.15.199 | ≥ 6.1.77, < 6.1.162 | ≥ 6.6.16, < 6.6.122 | ≥ 6.7.4, < 6.8 | ≥ 6.8.1, < 6.12.67 | ≥ 6.13, < 6.18.7 | 6.8 | 6.19:rc1 | 6.19:rc2 | 6.19:rc3 | 6.19:rc4 | 6.19:rc5 | 6.19:rc6 | 6.19:rc7 | 6.19:rc8
Debian1 product
  • linux< 6.1.162-1 | < 6.12.69-1 | < 6.18.8-1

3 vendors · 158 products

References

41 links
Show all 41 references