CVE-2026-98318
Description
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.
Statement
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.
Mitigation
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.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7 | N/A | 7.8 |
| Attack Vector | Local | N/A | Local |
| Attack Complexity | High | N/A | Low |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
Write operations could cause memory corruption. In some cases, an adversary can modify control data such as return addresses in order to execute unexpected code.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
Attempting to access out-of-range, invalid, or unauthorized memory could cause the product to crash.
Other
Technical Impact: Unexpected State
Subsequent write operations can produce undefined or unexpected results.
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