CVE-2025-23143 [Medium] | Security Vulnerability in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: net: Fix null-ptr-deref by sock_lock_init_class_and_name() and rmmod. When I ran the repro [0] and waited a few seconds, I observed two LOCKDEP splats: a warning immediately followed by a null-ptr-deref. [1] Reproduction Steps: 1) Mount CIFS 2) Add an iptables rule to drop incoming FIN packets for CIFS 3) Unmount CIFS 4) Unload the CIFS module 5) Remove the iptables rule At step 3), the CIFS module calls sock_release() for the underlying TCP socket, and it returns quickly. However, the socket remains in FIN_WAIT_1 because incoming FIN packets are dropped. At this point, the module's refcnt is 0 while the socket is still alive, so the following rmmod command succeeds. # ss -tan State Recv-Q Send-Q Local Address:Port Peer Address:Port FIN-WAIT-1 0 477 10.0.2.15:51062 10.0.0.137:445 # lsmod | grep cifs cifs 1159168 0 This highlights a discrepancy between the lifetime of the CIFS module and the underlying TCP socket. Even after CIFS calls sock_release() and it returns, the TCP socket does not die immediately in order to close the connection gracefully. While this is generally fine, it causes an issue with LOCKDEP because CIFS assigns a different lock class to the TCP socket's sk->sk_lock using sock_lock_init_class_and_name(). Once an incoming packet is processed for the socket or a timer fires, sk->sk_lock is acquired. Then, LOCKDEP checks the lock context in check_wait_context(), where hlock_class() is called to retrieve the lock class. However, since the module has already been unloaded, hlock_class() logs a warning and returns NULL, triggering the null-ptr-deref. If LOCKDEP is enabled, we must ensure that a module calling sock_lock_init_class_and_name() (CIFS, NFS, etc) cannot be unloaded while such a socket is still alive to prevent this issue. Let's hold the module reference in sock_lock_init_class_and_name() and release it when the socket is freed in sk_prot_free(). Note that sock_lock_init() clears sk->sk_owner for svc_create_socket() that calls sock_lock_init_class_and_name() for a listening socket, which clones a socket by sk_clone_lock() without GFP_ZERO. [0]: CIFS_SERVER="10.0.0.137" CIFS_PATH="//${CIFS_SERVER}/Users/Administrator/Desktop/CIFS_TEST" DEV="enp0s3" CRED="/root/WindowsCredential.txt" MNT=$(mktemp -d /tmp/XXXXXX) mount -t cifs ${CIFS_PATH} ${MNT} -o vers=3.0,credentials=${CRED},cache=none,echo_interval=1 iptables -A INPUT -s ${CIFS_SERVER} -j DROP for i in $(seq 10); do umount ${MNT} rmmod cifs sleep 1 done rm -r ${MNT} iptables -D INPUT -s ${CIFS_SERVER} -j DROP [1]: DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 10 PID: 0 at kernel/locking/lockdep.c:234 hlock_class (kernel/locking/lockdep.c:234 kernel/locking/lockdep.c:223) Modules linked in: cifs_arc4 nls_ucs2_utils cifs_md4 [last unloaded: cifs] CPU: 10 UID: 0 PID: 0 Comm: swapper/10 Not tainted 6.14.0 #36 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:hlock_class (kernel/locking/lockdep.c:234 kernel/locking/lockdep.c:223) ... Call Trace: <IRQ> __lock_acquire (kernel/locking/lockdep.c:4853 kernel/locking/lockdep.c:5178) lock_acquire (kernel/locking/lockdep.c:469 kernel/locking/lockdep.c:5853 kernel/locking/lockdep.c:5816) _raw_spin_lock_nested (kernel/locking/spinlock.c:379) tcp_v4_rcv (./include/linux/skbuff.h:1678 ./include/net/tcp.h:2547 net/ipv4/tcp_ipv4.c:2350) ... BUG: kernel NULL pointer dereference, address: 00000000000000c4 PF: supervisor read access in kernel mode PF: error_code(0x0000) - not-present page PGD 0 Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 10 UID: 0 PID: 0 Comm: swapper/10 Tainted: G W 6.14.0 #36 Tainted: [W]=WARN Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 RIP: 0010:__lock_acquire (kernel/ ---truncated---

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.02%	0.17%	+0.15%
2	2026-06-09	0.09%	0.02%	-0.07%
3	2026-02-25	—	0.09%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.02%

0.17%

+0.15%

2026-06-09

0.09%

0.02%

-0.07%

2026-02-25

—

0.09%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.5	3.1	MEDIUM	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	3.6	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.5

3.1

MEDIUM

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

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

3.6

[email protected]

OS Trackers for CVE-2025-23143

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2025-23143 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6.	https://security-tracker.debian.org/tracker/CVE-2025-23143
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2025-23143
`suse`	medium	CVE-2025-23143 severity moderate: SUSE including 25 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 89 product×package rows across 19 product lines (SUSE Linux Enterprise High Availability Extension 15 SP7, SUSE Linux Enterprise Live Patching 12 SP5, … (19 product lines)): Will Not Fix 89.	https://www.suse.com/security/cve/CVE-2025-23143/
`ubuntu`	medium	CVE-2025-23143 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, ignored 168, released 160, needed 44, not-affected 29, pending 3, needs-triage 2.	https://ubuntu.com/security/CVE-2025-23143

Affected software / configurations for CVE-2025-23143

Vendor	Product	Version	Raw CPE
linux	linux_kernel	>= 2.6.20, < 5.4.300	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.245	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.194	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 6.1.153	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.2, < 6.6.107	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.7, < 6.12.24	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.13, < 6.13.12	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 6.14, < 6.14.3	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.15	cpe:2.3:o:linux:linux_kernel:6.15:rc1::::::
debian	debian_linux	11.0	cpe:2.3:o:debian:debian_linux:11.0:::::::*

References for CVE-2025-23143

URL	Tags
https://git.kernel.org/stable/c/0bb2f7a1ad1f11d861f58e5ee5051c8974ff9569	Patch
https://git.kernel.org/stable/c/2155802d3313d7b8365935c6b8d6edc0ddd7eb94	Patch
https://git.kernel.org/stable/c/5f7f6abd92b6c8dc8f19625ef93c3a18549ede04	Patch
https://git.kernel.org/stable/c/83083c5fc7cf9b0f136a42f26aba60da380f3601	Patch
https://git.kernel.org/stable/c/905d43b8ad2436c240f844acb3ebcc7a99b8ebf1	Patch
https://git.kernel.org/stable/c/b7489b753667bc9245958a4896c9419743083c27	Patch
https://git.kernel.org/stable/c/c11247a21aab4b50a23c8b696727d7483de2f1e1	Patch
https://git.kernel.org/stable/c/d51e47e2ab6ef10a317d576075cf625cdbf96426	Patch
https://git.kernel.org/stable/c/feda73ad44a5cc80f6bf796bb1099a3fe71576d4	Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	Mailing List Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-032379.html

URL

CVE-2025-23143 | net: Fix null-ptr-deref by sock_lock_init_class_and_name() and rmmod.

Exploit prediction scoring system (EPSS) score for CVE-2025-23143

Common vulnerability scoring system (CVSS) metrics for CVE-2025-23143

Weakness enumeration for CVE-2025-23143

GitHub Security Advisory for CVE-2025-23143

OS Trackers for CVE-2025-23143

Affected software / configurations for CVE-2025-23143

References for CVE-2025-23143