Cloudanix VulnDB

CVE-2023-54265

None

CVSS

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EPSS

0.2%

Published

Dec 30, 2025

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A bug in the Linux kernel's network code could let a local user crash the system or peek at random memory by sending certain network packets.

Exploitation
Local Privilege
Attacker needs
Local User
Complexity
Moderate
Impact
Data Exposure
Component
OS kernel
Class
Memory Corruption
Remediation
Upgrade
Effort
Medium
Patch risk
Low

What it actually does

Uninitialized variable access in __ip6_make_skb when icmp6hdr is not in the skb linear region for SOCK_RAW IPv6 sockets, allowing direct access to icmp6_hdr(skb)->icmp6_type to read uninitialized kernel memory.

Why it matters to the business

Local attackers can trigger kernel instability, crashes, or potential information disclosure on systems running the affected Linux kernel versions, increasing operational risk for servers and devices using raw IPv6 sockets.

How an attack unfolds

An attacker opens a SOCK_RAW IPv6 socket and sends crafted messages via rawv6_sendmsg that reach __ip6_make_skb, causing the uninitialized icmp6_type access during packet construction for ICMPv6.

How to fix it

Update the Linux kernel to the fixed commit 165370522cc48127da564a08584a7391e6341908 or later stable versions containing the patch that uses a local icmp6_type variable.

How to confirm the fix worked

Confirm the kernel source includes the commit 165370522cc48127da564a08584a7391e6341908 and test raw IPv6 socket sendmsg paths with KMSAN or similar sanitizers to verify absence of uninit-value reports.

Typical attack path

  1. Open a SOCK_RAW IPv6 socket
  2. Prepare and send a message that triggers ip6_append_data and subsequent skb allocation
  3. Invoke rawv6_push_pending_frames leading to __ip6_make_skb
  4. Trigger direct access to uninitialized icmp6hdr fields

How to detect it

Review kernel logs for KMSAN uninit-value reports referencing __ip6_make_skb or ip6_output.c; inspect raw IPv6 socket usage in application traces or strace output.

What your security team should do

  • Prioritize kernel updates on systems exposing raw IPv6 sockets
  • Monitor for upstream stable releases incorporating the fix
  • Restrict unprivileged access to raw sockets via sysctl where feasible

The record

In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix an uninit variable access bug in __ip6_make_skb() Syzbot reported a bug as following: ===================================================== BUG: KMSAN: uninit-value in arch_atomic64_inc arch/x86/include/asm/atomic64_64.h:88 [inline] BUG: KMSAN: uninit-value in arch_atomic_long_inc include/linux/atomic/atomic-long.h:161 [inline] BUG: KMSAN: uninit-value in atomic_long_inc include/linux/atomic/atomic-instrumented.h:1429 [inline] BUG: KMSAN: uninit-value in __ip6_make_skb+0x2f37/0x30f0 net/ipv6/ip6_output.c:1956 arch_atomic64_inc arch/x86/include/asm/atomic64_64.h:88 [inline] arch_atomic_long_inc include/linux/atomic/atomic-long.h:161 [inline] atomic_long_inc include/linux/atomic/atomic-instrumented.h:1429 [inline] __ip6_make_skb+0x2f37/0x30f0 net/ipv6/ip6_output.c:1956 ip6_finish_skb include/net/ipv6.h:1122 [inline] ip6_push_pending_frames+0x10e/0x550 net/ipv6/ip6_output.c:1987 rawv6_push_pending_frames+0xb12/0xb90 net/ipv6/raw.c:579 rawv6_sendmsg+0x297e/0x2e60 net/ipv6/raw.c:922 inet_sendmsg+0x101/0x180 net/ipv4/af_inet.c:827 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xa8e/0xe70 net/socket.c:2476 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2530 __sys_sendmsg net/socket.c:2559 [inline] __do_sys_sendmsg net/socket.c:2568 [inline] __se_sys_sendmsg net/socket.c:2566 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2566 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was created at: slab_post_alloc_hook mm/slab.h:766 [inline] slab_alloc_node mm/slub.c:3452 [inline] __kmem_cache_alloc_node+0x71f/0xce0 mm/slub.c:3491 __do_kmalloc_node mm/slab_common.c:967 [inline] __kmalloc_node_track_caller+0x114/0x3b0 mm/slab_common.c:988 kmalloc_reserve net/core/skbuff.c:492 [inline] __alloc_skb+0x3af/0x8f0 net/core/skbuff.c:565 alloc_skb include/linux/skbuff.h:1270 [inline] __ip6_append_data+0x51c1/0x6bb0 net/ipv6/ip6_output.c:1684 ip6_append_data+0x411/0x580 net/ipv6/ip6_output.c:1854 rawv6_sendmsg+0x2882/0x2e60 net/ipv6/raw.c:915 inet_sendmsg+0x101/0x180 net/ipv4/af_inet.c:827 sock_sendmsg_nosec net/socket.c:714 [inline] sock_sendmsg net/socket.c:734 [inline] ____sys_sendmsg+0xa8e/0xe70 net/socket.c:2476 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2530 __sys_sendmsg net/socket.c:2559 [inline] __do_sys_sendmsg net/socket.c:2568 [inline] __se_sys_sendmsg net/socket.c:2566 [inline] __x64_sys_sendmsg+0x367/0x540 net/socket.c:2566 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd It is because icmp6hdr does not in skb linear region under the scenario of SOCK_RAW socket. Access icmp6_hdr(skb)->icmp6_type directly will trigger the uninit variable access bug. Use a local variable icmp6_type to carry the correct value in different scenarios.

Affected packages

Ecosystem Package Introduced Fixed
Linux Kernel 2.6.24 4.14.313

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