CVE-2025-38244

A flaw was found in the Linux kernel's Server Message Block (SMB) client. A local attacker could trigger a channel reconnection, leading to an incorrect lock order in the cifs_signal_cifsd_for_reconnect() function. This vulnerability can cause a circular locking dependency, resulting in a system deadlock and a Denial of Service (DoS) for the affected system.

A moderate-severity denial of service flaw exists in the Linux kernel SMB (CIFS) client in Red Hat Enterprise Linux 9 and 10. When an SMB3 mount uses multiple channels, a local attacker who can trigger a channel reconnection can cause cifs_signal_cifsd_for_reconnect() to acquire locks (chan_lock, ses_lock, srv_lock) in an incorrect order, creating a circular locking dependency. This results in a deadlock of the CIFS demultiplex thread and a denial of service on the affected system; only availability is impacted, with no effect on confidentiality or integrity. Earlier Red Hat Enterprise Linux versions (6, 7, and 8) and Red Hat In-Vehicle OS are not affected because the vulnerable code is not present in those kernels. For the affected RHEL 9 and RHEL 10 kernel and kernel-rt offerings, the fix is deferred to a future update; the residual risk is that a local user with access to an affected system can hang SMB/CIFS activity and cause a denial of service. Red Hat and NVD both rate this flaw Moderate (CVSS 5.5, local attack vector, low privileges required), which differs from the CVE.org rating of Important (CVSS 7.5, network attack vector): the evidence supports a local, privilege-requiring vector with availability-only impact.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.