CVE-2026-98286
Description
A flaw was found in the Linux kernel's drop_monitor subsystem. A local user can trigger this issue during monitor teardown under memory pressure, where a race condition allows a timer to be re-armed after it has been cancelled. When the module is subsequently unloaded, the active timer executes within freed memory, leading to a use-after-free vulnerability that can cause a Denial of Service (DoS) via a kernel crash.
Statement
A race in drop_monitor teardown can allow dm_alert_work to rearm a per CPU send_timer after timer_delete_sync has already returned. If the work is then cancelled and the module reference is released, the active timer may later invoke sched_send_work from unloaded module memory. This creates a use after free condition and can cause a kernel panic. For the CVSS the PR:H is selected because reliable triggering normally requires administrative control over drop_monitor teardown and module unloading. AC:H is selected because exploitation also depends on a narrow race window and a memory allocation failure while the worker is resetting per CPU state. The issue is not directly network reachable because packet traffic alone cannot perform the required teardown or unload operation. Impact is at least a local denial of service. In the paranoid case limited confidentiality or integrity impact is considered because execution can continue through a stale timer callback after module memory has been freed, although a reliable privilege escalation primitive is not established.
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 | 4.1 | N/A | N/A |
| Attack Vector | Local | N/A | N/A |
| Attack Complexity | High | N/A | N/A |
| Privileges Required | High | 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:H/PR:H/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Memory
The use of previously freed memory may corrupt valid data, if the memory area in question has been allocated and used properly elsewhere.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
If chunk consolidation occurs after the use of previously freed data, the process may crash when invalid data is used as chunk information.
Confidentiality
Technical Impact: Read Memory
Read operations on freed memory can sometimes leak sensitive information instead of causing a crash
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If malicious data is entered before chunk consolidation can take place, it may be possible to take advantage of a write-what-where primitive to execute arbitrary code. If the newly allocated data happens to hold a class, in C++ for example, various function pointers may be scattered within the heap data. If one of these function pointers is overwritten with an address to valid shellcode, execution of arbitrary code can be achieved.
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