CVE-2026-23238
Description
A flaw was found in the Linux kernel's romfs filesystem implementation. The romfs_fill_super() function ignores the return value of sb_set_blocksize(). When mounting a romfs filesystem on a device with an incompatible block size (larger than PAGE_SIZE), the mount proceeds with an incorrect block size, eventually triggering a kernel BUG in folio_set_bh() when attempting I/O operations.
Statement
This flaw requires the ability to configure a loop device's block size and mount a romfs filesystem on it. While the configuration sequence requires privileged access, once set up, the kernel BUG triggers during normal filesystem operations. Romfs is a read-only filesystem primarily used in embedded systems and initramfs.
Mitigation
To mitigate this issue, prevent the romfs module from being loaded. See https://access.redhat.com/solutions/41278 for instructions.
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 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability,Integrity
Technical Impact: Unexpected State; DoS: Crash, Exit, or Restart
An unexpected return value could place the system in a state that could lead to a crash or other unintended behaviors.
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