CVE-2026-98126
Description
A flaw was found in the Linux kernel's SMB client. This flaw allows a local user to bypass enforced file-size restrictions and expand files beyond authorized limits. When handling file allocation operations that zero out a range of data without preserving the file's existing size, the kernel fails to check whether the new size exceeds configured process file-size limits (RLIMIT_FSIZE). Consequently, a local user can write or extend files on mounted network shares beyond permitted resource boundaries.
Statement
A low impact flaw was found in the Linux kernel SMB client, affecting the kernel as shipped in Red Hat Enterprise Linux 8, 9, and 10, Red Hat In-Vehicle OS 2, and the RHEL CoreOS 8 and 9 kernels used in OpenShift Container Platform 4. When the fallocate() operation FALLOC_FL_ZERO_RANGE is used without FALLOC_FL_KEEP_SIZE on a file stored on a CIFS/SMB mount, smb3_zero_range() may extend the file beyond EOF without first checking the caller's RLIMIT_FSIZE limit. This allows a local user with write access to a file on the mounted share to grow that file beyond the file-size limit configured for their process. The consequence is a local resource-policy bypass with no direct confidentiality or integrity impact: the caller already has write access to the target file, and the main effect is potential storage consumption beyond the intended per-process boundary. Although the CVSS:3.1 base score is 5.5 (Moderate), Red Hat rates the overall impact as Low because exploitation requires local access and write permission on the target file, and the issue is limited to bypassing a per-process resource limit. Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present in those streams. Given the low impact, fixes for the affected products are currently deferred to future maintenance updates rather than delivered as immediate updates; the residual risk until a fix is delivered is limited to a local user exceeding file-size limits on SMB-mounted files, which server-side quotas and available-space limits can further constrain.
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 | 5.5 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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