CVE-2026-43303
Description
A flaw was found in the Linux kernel's memory management subsystem. When pages are freed, the page->private field is not properly cleared. If these pages are later reallocated as high-order pages and split, the tail pages can retain stale page->private values. This can lead to a use-after-free vulnerability in the swap subsystem, where incorrect assumptions about the page->private value can cause the system to crash.
Statement
A stale page private value can remain on freed pages and later survive allocation as a high-order page followed by split_page. The swap subsystem assumes newly allocated pages have page private set to zero and may treat the stale value as a valid swap count continuation, leading to traversal of poisoned or invalid list state and a UAF style wild memory access in the swapoff path. For the CVSS the PR:L is used for the paranoid case because a local user may be able to influence allocator state and page reuse even though the direct crash trace involves swapoff. The issue is not network reachable. Impact is at least local denial of service via kernel crash, and in worst case may allow confidentiality or integrity impact due to core memory management corruption.
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).
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)
Confidentiality
Technical Impact: Read Memory; Read Application Data
When reusing a resource such as memory or a program variable, the original contents of that resource may not be cleared before it is sent to an untrusted party.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The uninitialized resource may contain values that cause program flow to change in ways that the programmer did not intend.
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