CVE-2025-40271
Description
A flaw was found in the Linux kernel. This use-after-free (UAF) vulnerability occurs in the proc_readdir_de() function within the /proc filesystem. A local attacker with low privileges can exploit this by concurrently traversing specific directories while network devices are unregistered. This can lead to a use-after-free condition, potentially resulting in information disclosure, privilege escalation, or a denial of service (DoS).
Statement
The vulnerability is a race condition in /proc directory enumeration, where a proc_dir_entry can be freed after rb_erase() but still referenced because the rbtree node is not cleared. A local unprivileged attacker can trigger a use-after-free by running getdents() (that calls proc_readdir_de()) in parallel with rapid creation and removal of network-related proc entries (e.g., tun devices). In practice this leads to a kernel NULL-pointer dereference or slab-UAF crash. Reliable exploitation beyond denial-of-service is unlikely due to the narrow timing window, but theoretically possible. The bug could be triggered by the local attacker with the ability to create and remove network devices (e.g. CAP_NET_ADMIN).
Mitigation
Mitigation for this issue is either not available or the currently available options do not 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
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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