CVE-2026-23225
Description
A flaw was found in the Linux kernel. A local user can exploit a race condition in the sched/mmcid mode switch path. This occurs when a task exits with a specific flag (MM_CID_TRANSIT) still set, leading to an incorrect assumption that the Context ID (CID) is CPU-owned. This can result in an out-of-bounds bit operation, causing the kernel to crash, leading to a Denial of Service (DoS). In a worst-case scenario, this flaw could also lead to kernel memory corruption, potentially impacting system integrity and confidentiality.
Statement
A local race in the sched mmcid mode switch path can lead to an out of bounds bit operation when a task exits with the MM_CID_TRANSIT flag still set and the code incorrectly assumes the CID is CPU owned. This can cause clear_bit to be called with an extremely large bit index which can crash the kernel and may corrupt kernel memory. For the CVSS the PR is L because a normal local user can create and exit tasks and potentially hit the timing window during CID mode transitions. The issue is not network reachable and requires local execution on the host. Impact is at least denial of service due to a kernel crash. A conservative worst case also considers possible integrity and confidentiality impact if the out of bounds write can be steered into sensitive memory.
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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