CVE-2026-98318

A flaw was found in the Linux kernel's SMB (Server Message Block) client. When handling absolute symbolic links on mounted shares, the client fails to validate the link target format before applying Windows NT path adjustments. A user with write access to a mounted share can exploit this vulnerability by creating a specially crafted symbolic link, triggering out-of-bounds memory writes and a buffer overflow. This flaw can result in a Denial of Service (DoS) by crashing the system or potentially allow arbitrary code execution.

Red Hat rates this Linux kernel flaw as Important. A flaw was found in the Linux kernel's SMB client: when the symlinkroot mount option is unset, an absolute symbolic link target created on a mounted SMB share is copied without conversion to an NT drive path, while later code still assumes an NT prefix is present when modifying the target and calculating its print name length. This results in out-of-bounds writes past the allocated buffers and an integer underflow that causes a large buffer overflow (a 65534-byte memcpy into a 24-byte buffer). A local user with write access to a mounted SMB share can trigger this flaw using default settings, resulting in a kernel crash (denial of service) or potentially arbitrary code execution. Red Hat Enterprise Linux 9 and 10 streams and Red Hat In-Vehicle OS 2 are affected, and a fix is being pursued for those products. Earlier Red Hat Enterprise Linux 6, 7, and 8 releases, the RHEL 9.2/9.4/9.6 and RHEL 10.0 maintenance streams, and the OpenShift Container Platform RHEL CoreOS 8 and 9 images are not affected because the vulnerable code is not present in them. Red Hat's CVSS score of 7.0 (AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H) differs from the upstream CVEORG score of 7.8 mainly in the assessed attack complexity.

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.