CVE-2023-54051
NoneCVSS
—
EPSS
0.2%
Published
Dec 24, 2025
CISA due date
—
Cloudanix analysis
A bug in the Linux kernel's handling of certain network packets could let an attacker crash the entire system, interrupting network services until the machine is restarted.
- Exploitation
- Local Privilege
- Attacker needs
- Low Privilege
- Complexity
- Low
- Impact
- Denial Of Service
- Component
- OS kernel
- Class
- Improper Input Validation
- Remediation
- Upgrade
- Effort
- Medium
- Patch risk
- Low
What it actually does
Missing input validation in virtio_net_hdr_to_skb() permits gso_size to be set to the internal sentinel value GSO_BY_FRAGS (0xffff), resulting in a null pointer dereference during skb_segment processing of GSO packets.
Why it matters to the business
Attackers can trigger kernel crashes on systems accepting crafted network traffic, causing denial of service and potential loss of availability for network-dependent services until the host is rebooted.
How an attack unfolds
An attacker crafts a malicious UDP or packet-socket frame with gso_size set to 0xffff, sends it through the AF_PACKET interface, and triggers GSO segmentation in the transmit path, causing skb_segment to dereference an invalid pointer and panic the kernel.
How to fix it
Update the Linux kernel to a version containing commit a5f9e5804d239d288d983db36bbed45ed10729a0 or later; apply the corresponding stable or distribution kernel package that enforces the gso_size != GSO_BY_FRAGS check in virtio_net_hdr_to_skb().
How to confirm the fix worked
Confirm the running kernel contains the referenced commit or a backported equivalent; attempt to reproduce the syzbot reproducer and verify it no longer triggers a crash; review kernel logs for absence of the previous null-ptr-deref in skb_segment.
Typical attack path
- Obtain local or remote access to a system that processes untrusted packets via packet sockets or virtio networking
- Construct a network frame or UDP datagram setting the gso_size field to GSO_BY_FRAGS
- Invoke sendmsg or equivalent on an AF_PACKET or UDP socket to queue the frame for transmission
- Trigger GSO segmentation via ipv6_gso_segment or udp6_ufo_fragment during dev_queue_xmit
- Cause skb_segment to perform an invalid memory access leading to a general protection fault and kernel panic
How to detect it
Search kernel logs for general protection faults mentioning skb_segment and null-ptr-deref around UDP or packet transmit paths; look for unusual AF_PACKET sendmsg activity from unprivileged processes preceding crashes.
What your security team should do
- Prioritize kernel updates on all systems exposing packet sockets or virtio networking to untrusted traffic
- Apply the fix within normal patch windows given low EPSS and no known in-the-wild exploitation
- Monitor upstream stable kernel releases for additional related GSO handling hardening
- Restrict unprivileged use of AF_PACKET sockets where feasible via system policy
The record
In the Linux kernel, the following vulnerability has been resolved: net: do not allow gso_size to be set to GSO_BY_FRAGS One missing check in virtio_net_hdr_to_skb() allowed syzbot to crash kernels again [1] Do not allow gso_size to be set to GSO_BY_FRAGS (0xffff), because this magic value is used by the kernel. [1] general protection fault, probably for non-canonical address 0xdffffc000000000e: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000070-0x0000000000000077] CPU: 0 PID: 5039 Comm: syz-executor401 Not tainted 6.5.0-rc5-next-20230809-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023 RIP: 0010:skb_segment+0x1a52/0x3ef0 net/core/skbuff.c:4500 Code: 00 00 00 e9 ab eb ff ff e8 6b 96 5d f9 48 8b 84 24 00 01 00 00 48 8d 78 70 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e ea 21 00 00 48 8b 84 24 00 01 RSP: 0018:ffffc90003d3f1c8 EFLAGS: 00010202 RAX: dffffc0000000000 RBX: 000000000001fffe RCX: 0000000000000000 RDX: 000000000000000e RSI: ffffffff882a3115 RDI: 0000000000000070 RBP: ffffc90003d3f378 R08: 0000000000000005 R09: 000000000000ffff R10: 000000000000ffff R11: 5ee4a93e456187d6 R12: 000000000001ffc6 R13: dffffc0000000000 R14: 0000000000000008 R15: 000000000000ffff FS: 00005555563f2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020020000 CR3: 000000001626d000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> udp6_ufo_fragment+0x9d2/0xd50 net/ipv6/udp_offload.c:109 ipv6_gso_segment+0x5c4/0x17b0 net/ipv6/ip6_offload.c:120 skb_mac_gso_segment+0x292/0x610 net/core/gso.c:53 __skb_gso_segment+0x339/0x710 net/core/gso.c:124 skb_gso_segment include/net/gso.h:83 [inline] validate_xmit_skb+0x3a5/0xf10 net/core/dev.c:3625 __dev_queue_xmit+0x8f0/0x3d60 net/core/dev.c:4329 dev_queue_xmit include/linux/netdevice.h:3082 [inline] packet_xmit+0x257/0x380 net/packet/af_packet.c:276 packet_snd net/packet/af_packet.c:3087 [inline] packet_sendmsg+0x24c7/0x5570 net/packet/af_packet.c:3119 sock_sendmsg_nosec net/socket.c:727 [inline] sock_sendmsg+0xd9/0x180 net/socket.c:750 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2496 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2550 __sys_sendmsg+0x117/0x1e0 net/socket.c:2579 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7ff27cdb34d9
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 4.8.0 | 4.14.324 |
| SUSE:Linux Enterprise High Availability Extension 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Live Patching 15 SP4 | kernel-livepatch-SLE15-SP4_Update_48 | 0 | 1-150400.9.7.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Live Patching 15 SP6 | kernel-livepatch-SLE15-SP6_Update_19 | 0 | 1-150600.13.3.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.3 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.4 | kernel-source-rt | 0 | 5.14.21-150400.15.142.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Micro 5.5 | kernel-source-rt | 0 | 5.14.21-150500.13.118.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-64kb | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP4-LTSS | kernel-zfcpdump | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server 15 SP6-LTSS | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default-base | 0 | 5.14.21-150400.24.194.1.150400.24.98.3 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-docs | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-obs-build | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | kernel-syms | 0 | 5.14.21-150400.24.194.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| SUSE:Linux Enterprise Server for SAP Applications 15 SP6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | dtb-aarch64 | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-64kb | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-debug | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-default-base | 0 | 6.4.0-150600.23.84.1.150600.12.38.1 |
| openSUSE:Leap 15.6 | kernel-docs | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-kvmsmall | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-build | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-obs-qa | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-source | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-syms | 0 | 6.4.0-150600.23.84.1 |
| openSUSE:Leap 15.6 | kernel-zfcpdump | 0 | 6.4.0-150600.23.84.1 |
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