CVE-2026-46065
Description
A flaw was found in the Linux kernel's framebuffer device (fbdev) deferred I/O (defio) mechanism. A local user with an active mapping of graphics memory could trigger a device hot-unplug, leading to the system accessing undefined memory. This can result in system instability or a crash, causing a Denial of Service (DoS).
Statement
fbdev deferred I/O used a mapping-private pointer to fb_info while user space could keep an active mmap after device hot-unplug. If fb_info was freed before the last VMA was closed, later fault or page_mkwrite handling could operate on stale kernel state and trigger a use-after-free. For the CVSS the PR:L is selected because practical triggering requires local access to the framebuffer device and an active mmap, but this does not necessarily require full host root in systems where /dev/fb access is delegated to a local user or graphics group. The issue is not network reachable and normally depends on a hot-unplug or device removal event, so AC:H is appropriate. Impact is at least local denial of service via kernel crash.
Mitigation
Mitigation for this issue is either not available or the currently available options don't 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 | 5.8 | 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 | Low | N/A | High |
| Integrity Impact | Low | 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:L/I:L/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)
Confidentiality
Technical Impact: Read Memory
If the expired pointer is used in a read operation, an attacker might be able to control data read in by the application.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If the expired pointer references a memory location that is not accessible to the product, or points to a location that is "malformed" (such as NULL) or larger than expected by a read or write operation, then a crash may occur.
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If the expired pointer is used in a function call, or points to unexpected data in a write operation, then code execution may be possible.
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