Skip to main content

Linux Kernel CVE-2025-38379

MEDIUM
2025-07-25 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Information Disclosure Linux Red Hat Suse
5.5
CVSS 3.1 · NVD
Share

Severity by source

NVD PRIMARY
5.5 MEDIUM
AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
5.5 MEDIUM

Local trigger via SMB mount requires low privilege; no confidentiality or integrity impact; kernel crash yields high availability impact within the same system.

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
MEDIUM
qualitative
Red Hat
5.5 MEDIUM
qualitative

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

2
Analysis Generated
Jul 30, 2026 - 08:56 vuln.today
CVE Published
Jul 25, 2025 - 13:15 nvd
MEDIUM 5.5

DescriptionNVD

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix warning when reconnecting channel

When reconnecting a channel in smb2_reconnect_server(), a dummy tcon is passed down to smb2_reconnect() with ->query_interface uninitialized, so we can't call queue_delayed_work() on it.

Fix the following warning by ensuring that we're queueing the delayed worker from correct tcon.

WARNING: CPU: 4 PID: 1126 at kernel/workqueue.c:2498 __queue_delayed_work+0x1d2/0x200 Modules linked in: cifs cifs_arc4 nls_ucs2_utils cifs_md4 [last unloaded: cifs] CPU: 4 UID: 0 PID: 1126 Comm: kworker/4:0 Not tainted 6.16.0-rc3 #5 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-4.fc42 04/01/2014 Workqueue: cifsiod smb2_reconnect_server [cifs] RIP: 0010:__queue_delayed_work+0x1d2/0x200 Code: 41 5e 41 5f e9 7f ee ff ff 90 0f 0b 90 e9 5d ff ff ff bf 02 00 00 00 e8 6c f3 07 00 89 c3 eb bd 90 0f 0b 90 e9 57 f> 0b 90 e9 65 fe ff ff 90 0f 0b 90 e9 72 fe ff ff 90 0f 0b 90 e9 RSP: 0018:ffffc900014afad8 EFLAGS: 00010003 RAX: 0000000000000000 RBX: ffff888124d99988 RCX: ffffffff81399cc1 RDX: dffffc0000000000 RSI: ffff888114326e00 RDI: ffff888124d999f0 RBP: 000000000000ea60 R08: 0000000000000001 R09: ffffed10249b3331 R10: ffff888124d9998f R11: 0000000000000004 R12: 0000000000000040 R13: ffff888114326e00 R14: ffff888124d999d8 R15: ffff888114939020 FS: 0000000000000000(0000) GS:ffff88829f7fe000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe7a2b4038 CR3: 0000000120a6f000 CR4: 0000000000750ef0 PKRU: 55555554 Call Trace: <TASK> queue_delayed_work_on+0xb4/0xc0 smb2_reconnect+0xb22/0xf50 [cifs] smb2_reconnect_server+0x413/0xd40 [cifs] ? __pfx_smb2_reconnect_server+0x10/0x10 [cifs] ? local_clock_noinstr+0xd/0xd0 ? local_clock+0x15/0x30 ? lock_release+0x29b/0x390 process_one_work+0x4c5/0xa10 ? __pfx_process_one_work+0x10/0x10 ? __list_add_valid_or_report+0x37/0x120 worker_thread+0x2f1/0x5a0 ? __kthread_parkme+0xde/0x100 ? __pfx_worker_thread+0x10/0x10 kthread+0x1fe/0x380 ? kthread+0x10f/0x380 ? __pfx_kthread+0x10/0x10 ? local_clock_noinstr+0xd/0xd0 ? ret_from_fork+0x1b/0x1f0 ? local_clock+0x15/0x30 ? lock_release+0x29b/0x390 ? rcu_is_watching+0x20/0x50 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x15b/0x1f0 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 </TASK> irq event stamp: 1116206 hardirqs last enabled at (1116205): [<ffffffff8143af42>] __up_console_sem+0x52/0x60 hardirqs last disabled at (1116206): [<ffffffff81399f0e>] queue_delayed_work_on+0x6e/0xc0 softirqs last enabled at (1116138): [<ffffffffc04562fd>] __smb_send_rqst+0x42d/0x950 [cifs] softirqs last disabled at (1116136): [<ffffffff823d35e1>] release_sock+0x21/0xf0

AnalysisAI

Kernel warning triggering denial of service in the Linux SMB client subsystem affects systems using SMB multichannel. During channel reconnection in smb2_reconnect_server(), a dummy tcon structure with an uninitialized ->query_interface pointer is incorrectly passed to smb2_reconnect(), which then calls queue_delayed_work() on the invalid struct, firing a WARN_ON in the kernel workqueue at __queue_delayed_work+0x1d2/0x200. The result is potential kernel instability or crash on any Linux host using CIFS multichannel mounts; no active exploitation is confirmed, EPSS is 0.15% (4th percentile), and upstream patch commits are available across multiple stable branches.

Technical ContextAI

The vulnerability resides in the CIFS/SMB2 client subsystem (cifs.ko) of the Linux kernel, specifically in smb2_reconnect_server() and its callee smb2_reconnect(). The SMB multichannel feature allows a single SMB session to use multiple network channels for throughput and resilience; when a channel reconnects, a synthetic dummy tcon (tree connection) object is constructed and passed through the reconnection path. This dummy object is not fully initialized - its ->query_interface field is left unset - but smb2_reconnect() proceeds to call queue_delayed_work() on it as if it were a real tcon, violating the workqueue precondition checked at kernel/workqueue.c:2498. No CWE is formally assigned, but the root cause is functionally CWE-824 (Access of Uninitialized Pointer). Affected CPEs include cpe:2.3:o:linux:linux_kernel:6.16:rc1 through rc4, with broader wildcard CPE entries indicating earlier stable kernel series are also impacted. The cifs, cifs_arc4, nls_ucs2_utils, and cifs_md4 modules are involved per the stack trace.

RemediationAI

Apply the upstream kernel patches from the stable repository: https://git.kernel.org/stable/c/0cee638d92ac898d73eccc4e4bab70e9fc95946a, https://git.kernel.org/stable/c/3bbe46716092d8ef6b0df4b956f585c5cd0fc78e, https://git.kernel.org/stable/c/3f6932ef25378794894c3c1024092ad14da2d330, and https://git.kernel.org/stable/c/9d2b629a9dc5c72537645533af1cb11a7d34c4b1. An exact patched stable release version is not independently confirmed beyond these upstream commits - monitor your Linux distribution's security advisories for a kernel update that incorporates these fixes. As a compensating control, disabling SMB multichannel (by omitting the 'multichannel' mount option or setting max_channels=1 in smb3 mounts) prevents the channel reconnection code path entirely, eliminating exposure; the trade-off is loss of SMB multichannel throughput and redundancy benefits. Systems not mounting SMB shares with multichannel are not exposed to this path and require no immediate action.

Same technique Information Disclosure

View all
CVE-2019-2725 CRITICAL POC
9.8
CVE-2021-34523 CRITICAL POC
9.0
CVE-2013-2251 CRITICAL POC
9.8
CVE-2017-5638 CRITICAL POC
9.8
CVE-2025-24813 CRITICAL POC
9.8
CVE-2015-1701 HIGH POC
7.8
CVE-2017-0147 HIGH POC
7.5
CVE-2014-6324 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container suse/sl-micro/6.0/baremetal-os-container:latest Container suse/sl-micro/6.0/toolbox:latest Affected
Container suse/sl-micro/6.0/base-os-container:2.1.3-7.95 Image SL-Micro Image SLE-Micro Image SLE-Micro-Azure Image SLE-Micro-BYOS Image SLE-Micro-BYOS-Azure Image SLE-Micro-BYOS-EC2 Image SLE-Micro-BYOS-GCE Image SLE-Micro-EC2 Image SLE-Micro-GCE Affected
Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.115 Affected
Container suse/sl-micro/6.0/rt-os-container:2.1.3-7.146 Affected
Container suse/sl-micro/6.1/base-os-container:2.2.1-5.80 Image SL-Micro-Azure Image SL-Micro-BYOS-Azure Image SL-Micro-BYOS-EC2 Image SL-Micro-BYOS-GCE Image SL-Micro-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-Azure Image SUSE-Multi-Linux-Manager-Proxy-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Proxy-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-Azure-llc Image SUSE-Multi-Linux-Manager-Server-Azure-ltd Image SUSE-Multi-Linux-Manager-Server-BYOS-Azure Image SUSE-Multi-Linux-Manager-Server-BYOS-EC2 Image SUSE-Multi-Linux-Manager-Server-BYOS-GCE Image SUSE-Multi-Linux-Manager-Server-EC2-llc Image SUSE-Multi-Linux-Manager-Server-EC2-ltd Affected

Share

CVE-2025-38379 vulnerability details – vuln.today
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy