CVE-2023-54006
NoneCVSS
—
EPSS
0.2%
Published
Dec 24, 2025
CISA due date
—
Cloudanix analysis
A bug in the operating system's handling of connections between programs on the same machine could cause crashes or instability when many programs communicate at once.
- Exploitation
- Local Privilege
- Attacker needs
- Local User
- Complexity
- High
- Impact
- Other
- Component
- OS kernel
- Class
- Race Condition
- Remediation
- Patch
- Effort
- Medium
- Patch risk
- Low
What it actually does
The vulnerability is a data race on the unix_tot_inflight variable in the AF_UNIX socket implementation, where writes occur under spin_lock(unix_gc_lock) but reads in unix_release_sock occur locklessly without READ_ONCE, allowing inconsistent counter values during concurrent socket operations involving file descriptor passing.
Why it matters to the business
Systems relying on Unix domain sockets may experience kernel instability, crashes, or unreliable socket garbage collection under concurrent load, reducing availability of applications that use local inter-process communication.
How an attack unfolds
An attacker triggers concurrent AF_UNIX datagram sends with SCM_RIGHTS file descriptors while sockets are released, racing the marked write to unix_tot_inflight against the lockless read to produce an inconsistent counter value that could affect garbage collection or lead to denial of service; no public exploits or threat actor usage are known.
How to fix it
Apply the upstream kernel fix that annotates the read with READ_ONCE() and ensures consistent locking; for affected vantage6/vantage6 deployments update to the revision containing commit 5ee1ecbf44525a8221d528743e0832912591b248.
How to confirm the fix worked
Confirm the kernel source contains READ_ONCE() on unix_tot_inflight accesses in unix_release_sock and unix_inflight paths, recompile or update the kernel, and run KCSAN or similar concurrency checkers to verify absence of the reported race.
Typical attack path
- Establish multiple concurrent AF_UNIX sockets
- Perform sendmsg operations passing file descriptors
- Trigger socket close or release during active sends
- Exploit resulting inconsistent unix_tot_inflight value for kernel impact
How to detect it
Scan kernel logs and KCSAN reports for data-race warnings involving unix_inflight and unix_release_sock functions; monitor for unexpected socket release or garbage collection anomalies under load.
What your security team should do
- Prioritize kernel updates containing the READ_ONCE fix across all affected systems
- Include Unix socket-heavy workloads in concurrency sanitizer testing
- Review socket usage patterns and consider alternatives where feasible until patched
The record
In the Linux kernel, the following vulnerability has been resolved: af_unix: Fix data-race around unix_tot_inflight. unix_tot_inflight is changed under spin_lock(unix_gc_lock), but unix_release_sock() reads it locklessly. Let's use READ_ONCE() for unix_tot_inflight. Note that the writer side was marked by commit 9d6d7f1cb67c ("af_unix: annote lockless accesses to unix_tot_inflight & gc_in_progress") BUG: KCSAN: data-race in unix_inflight / unix_release_sock write (marked) to 0xffffffff871852b8 of 4 bytes by task 123 on cpu 1: unix_inflight+0x130/0x180 net/unix/scm.c:64 unix_attach_fds+0x137/0x1b0 net/unix/scm.c:123 unix_scm_to_skb net/unix/af_unix.c:1832 [inline] unix_dgram_sendmsg+0x46a/0x14f0 net/unix/af_unix.c:1955 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg+0x148/0x160 net/socket.c:747 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2493 ___sys_sendmsg+0xc6/0x140 net/socket.c:2547 __sys_sendmsg+0x94/0x140 net/socket.c:2576 __do_sys_sendmsg net/socket.c:2585 [inline] __se_sys_sendmsg net/socket.c:2583 [inline] __x64_sys_sendmsg+0x45/0x50 net/socket.c:2583 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x72/0xdc read to 0xffffffff871852b8 of 4 bytes by task 4891 on cpu 0: unix_release_sock+0x608/0x910 net/unix/af_unix.c:671 unix_release+0x59/0x80 net/unix/af_unix.c:1058 __sock_release+0x7d/0x170 net/socket.c:653 sock_close+0x19/0x30 net/socket.c:1385 __fput+0x179/0x5e0 fs/file_table.c:321 ____fput+0x15/0x20 fs/file_table.c:349 task_work_run+0x116/0x1a0 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x174/0x180 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:297 do_syscall_64+0x4b/0x90 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x72/0xdc value changed: 0x00000000 -> 0x00000001 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 4891 Comm: systemd-coredum Not tainted 6.4.0-rc5-01219-gfa0e21fa4443 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
Affected packages
| Ecosystem | Package | Introduced | Fixed |
|---|---|---|---|
| Linux | Kernel | 2.6.24 | 4.14.326 |
| SUSE:Linux Enterprise High Availability Extension 15 SP6 | kernel-default | 0 | 6.4.0-150600.23.84.1 |
| 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 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 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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