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NVD / CVE Program· CNA Linux

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

MediumCVSS 5.5 · v3.1—Proof of concept Fix available

Noroxi assessment

Priority: Monitor (action score 22/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.54% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: Linux Linux 2f03dafea0a8096a2eb60f551218b360e5bab9a3, 5.10.249, 5.15.199.
  • Severity is disputed: the assigning authority (CNA) scores it 7.5, NVD 5.5.

Low priority for now. Upgrade to Linux Linux 2f03dafea0a8096a2eb60f551218b360e5bab9a3, 5.10.249, 5.15.199 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

Published
Jan 25, 2026
Updated
Nov 10, 2026
EPSS
0.5% · 46th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · Linux
7.5
2.0 point gap

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-23003

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  • when exploit code appears or is weaponized
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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • c835df3bcc14858ae9b27315dd7de76370b94f3a, 6.8affected
    • a9bc32879a08f23cdb80a48c738017e39aea1080 and later · before f9c5c5b791d3850570796f9e067629474e613796affected · git
    • af6b5c50d47ab43e5272ad61935d0ed2e264d3f0 and later · before 64c71d60a21a9ed0a802483dcd422b5b24eb1abeaffected · git
    • d54e4da98bbfa8c257bdca94c49652d81d18a4d8 and later · before 9e1c8c2a33d0a7b1f637b5d0602fe56ed10166afaffected · git
    • 350a6640fac4b53564ec20aa3f4a0922cb0ba5e6 and later · before 2f03dafea0a8096a2eb60f551218b360e5bab9a3affected · git
    • 8d975c15c0cd744000ca386247432d57b21f9df0 and later · before df5ffde9669314500809bc498ae73d6d3d9519acaffected · git
    • 8d975c15c0cd744000ca386247432d57b21f9df0 and later · before b9f915340f25cae1562f18e1eb52deafca328414affected · git
    • 8d975c15c0cd744000ca386247432d57b21f9df0 and later · before 81c734dae203757fb3c9eee6f9896386940776bdaffected · git
    • 5.10.210 and later · before 5.10.249affected · semver
    • 5.15.149 and later · before 5.15.199affected · semver
Affected versions · NVD (9)

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel5.10.210 and later · before 5.10.249
  • linux linux kernel5.15.149 and later · before 5.15.199
  • linux linux kernel6.1.77 and later · before 6.1.162
  • linux linux kernel6.6.16 and later · before 6.6.122
  • linux linux kernel6.7.4 and later · before 6.8
  • linux linux kernel6.8.1 and later · before 6.12.67
  • linux linux kernel6.13 and later · before 6.18.7
  • linux linux kernel6.19
  • linux linux kernel6.8

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10kernelbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64kbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-debug-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-64k-modules-extrabefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-abi-stablelistsbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-cross-headersbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debugbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-develbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-devel-matchedbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modulesbefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2
AlmaLinux:10kernel-debug-modules-corebefore 6.12.0-211.50.1.el10_26.12.0-211.50.1.el10_2

+96

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe…KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-23001Jan 25, 2026 · macvlan: fix possible UAF in macvlan_forward_source()
    31Monitor
  • ← EarlierCVE-2026-23002Jan 25, 2026 · lib/buildid: use __kernel_read() for sleepable context
    22Monitor
  • Later →CVE-2026-23004Jan 25, 2026 · dst: fix races in rt6_uncached_list_del() and rt_del_uncached_list()
    18Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux2f03dafea0a8096a2eb60f551218b360e5bab9a3Vendor (CNA)
Linux Linux5.10.249Vendor (CNA)
Linux Linux5.15.199Vendor (CNA)
Linux Linux6.1.162Vendor (CNA)
Linux Linux6.6.122Vendor (CNA)
Linux Linux6.8Vendor (CNA)
Linux Linux64c71d60a21a9ed0a802483dcd422b5b24eb1abeVendor (CNA)
Linux Linux81c734dae203757fb3c9eee6f9896386940776bdVendor (CNA)
Linux Linux9e1c8c2a33d0a7b1f637b5d0602fe56ed10166afVendor (CNA)
Linux Linuxb9f915340f25cae1562f18e1eb52deafca328414Vendor (CNA)
Linux Linuxdf5ffde9669314500809bc498ae73d6d3d9519acVendor (CNA)
Linux Linuxf9c5c5b791d3850570796f9e067629474e613796Vendor (CNA)
almalinux:kernel5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-core5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-core5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-devel-matched5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-core5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-debug-modules-extra5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
almalinux:kernel-64k-devel-matched5.14.0-687.42.1.el9_8 · AlmaLinux:9Package registry (OSV)
debian:linux6.1.162-1 · Debian:12Package registry (OSV)
red hat:kernel-64k-debug-debuginfo0:5.14.0-687.42.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel0:5.14.0-687.42.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debug-devel-matched0:5.14.0-687.42.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-debuginfo0:5.14.0-687.42.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)
red hat:kernel-64k-devel0:5.14.0-687.42.1.el9_8 · Red Hat:enterprise_linux:9::appstreamPackage registry (OSV)

+12

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:12026-08-05

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+191 d
  3. TodayNov 12, 2026+291 d

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2024-50302432 days apartHID: core: zero-initialize the report bufferKEV
    52Plan
  • CVE-2026-52989150 days apartnvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
    39Monitor
  • CVE-2026-53225151 days apartsctp: fix uninit-value in __sctp_rcv_asconf_lookup()
    36Monitor
  • CVE-2024-47685461 days apartnetfilter: nf_reject_ipv6: fix nf_reject_ip6_tcphdr_put()
    36Monitor
  • CVE-2026-53170151 days apartaccel/ethosu: reject DMA commands with uninitialized length
    35Monitor
  • CVE-2026-43139101 days apartxfrm6: fix uninitialized saddr in xfrm6_get_saddr()
    34Monitor

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-908 · Use of Uninitialized Resource

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (8 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records