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

smb: client: Fix use-after-free in cifs_try_adding_channels()

cifs_try_adding_channels() takes a temporary reference to an interface
before dropping iface_lock. If cifs_ses_add_channel() fails, it drops
that reference and then increments iface->weight_fulfilled.

A concurrent interface list refresh can remove the list reference while
channel creation is in progress. In that case, the failure-path
kref_put() releases the last reference and frees iface. Updating
weight_fulfilled afterward then accesses freed memory.

Increment weight_fulfilled before dropping the temporary reference,
keeping iface alive for the final access.
Published: 2026-08-22
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: Use-After-Free Leading to Potential Memory Corruption
Action: Apply Patch
AI Analysis

Impact

The Linux kernel’s CIFS SMB client contains a use‑after‑free flaw (CWE‑825) in the function cifs_try_adding_channels(). When cifs_ses_add_channel() fails, a reference to the interface structure is released before weight_fulfilled is updated. If a concurrent interface list refresh removes the reference mid‑operation, the last reference is freed and the interface object is deallocated. A subsequent update of weight_fulfilled then dereferences freed memory, creating an opportunity for a malicious attacker to trigger memory corruption or potentially gain arbitrary code execution on the host. The description does not describe a demonstrated exploitation path, but the nature of the fault indicates a serious kernel memory safety violation.

Affected Systems

Based on the description, all Linux kernel releases that contain the CIFS SMB client implementation prior to the patch commit appear to be affected. The vulnerability is not limited to a particular distribution, architecture, or kernel version, and any kernel that includes the vulnerable code, up to the point of the fix, is susceptible. This inference is drawn because the CVE description references the kernel CIFS client code without imposing specific version constraints.

Risk and Exploitability

The CVSS score of 9.8 identifies the flaw as critical, while the EPSS score of < 1 % indicates a very low publicly observed exploitation probability. Because use‑after‑free bugs in the kernel can lead to arbitrary code execution or denial of service, the risk remains high. The vulnerability is not listed in the CISA KEV catalog, suggesting that no widespread exploits have been reported yet. Attacks would likely target a CIFS client that attempts to create a channel, forces a failure, and concurrently triggers an interface list refresh, which would require specific traffic patterns or conditions on the client or server side. Nonetheless, the potential impact warrants prompt remediation.

Generated by OpenCVE AI on August 25, 2026 at 18:28 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update the Linux kernel to a version that contains the patch that fixes cifs_try_adding_channels()
  • Reboot the system so that the updated kernel and CIFS subsystem load
  • If a kernel update cannot be applied immediately, consider disabling CIFS SMB client services or unmounting CIFS filesystems to reduce the attack surface

Generated by OpenCVE AI on August 25, 2026 at 18:28 UTC.

Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4777-1 linux security update
Debian DSA Debian DSA DSA-6466-1 linux security update
History

Tue, 25 Aug 2026 15:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362
CWE-416

Tue, 25 Aug 2026 12:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

threat_severity

Moderate


Tue, 25 Aug 2026 08:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362
CWE-416

Tue, 25 Aug 2026 06:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Tue, 25 Aug 2026 05:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Sat, 22 Aug 2026 17:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Sat, 22 Aug 2026 15:45:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: smb: client: Fix use-after-free in cifs_try_adding_channels() cifs_try_adding_channels() takes a temporary reference to an interface before dropping iface_lock. If cifs_ses_add_channel() fails, it drops that reference and then increments iface->weight_fulfilled. A concurrent interface list refresh can remove the list reference while channel creation is in progress. In that case, the failure-path kref_put() releases the last reference and frees iface. Updating weight_fulfilled afterward then accesses freed memory. Increment weight_fulfilled before dropping the temporary reference, keeping iface alive for the final access.
Title smb: client: Fix use-after-free in cifs_try_adding_channels()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-25T05:40:33.533Z

Reserved: 2026-08-15T05:44:03.920Z

Link: CVE-2026-74608

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-08-22T16:16:33.290

Modified: 2026-08-25T06:18:37.637

Link: CVE-2026-74608

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-22T00:00:00Z

Links: CVE-2026-74608 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-25T18:30:04Z

Weaknesses
  • CWE-825

    Expired Pointer Dereference