CVE-2023-4208 Use-after-free in Linux kernel's net/sched: cls_u32 component

2023-09-0613:53:23

CWE-416

Google

www.cve.org

vulnerability

linux kernel

net/sched

cls_u32

use-after-free

local privilege escalation

tcf_result

tcf_unbind_filter

filter_cnt

commit 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81

7.8 High

CVSS3

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

7.8 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

5.1%

JSON

A use-after-free vulnerability in the Linux kernel’s net/sched: cls_u32 component can be exploited to achieve local privilege escalation.

When u32_change() is called on an existing filter, the whole tcf_result struct is always copied into the new instance of the filter. This causes a problem when updating a filter bound to a class, as tcf_unbind_filter() is always called on the old instance in the success path, decreasing filter_cnt of the still referenced class and allowing it to be deleted, leading to a use-after-free.

We recommend upgrading past commit 3044b16e7c6fe5d24b1cdbcf1bd0a9d92d1ebd81.

CNA Affected

[
  {
    "vendor": "Linux",
    "product": "Kernel",
    "packageName": "kernel",
    "repo": "https://git.kernel.org",
    "versions": [
      {
        "status": "affected",
        "version": "3.18",
        "lessThan": "6.5",
        "versionType": "custom"
      }
    ],
    "defaultStatus": "unaffected"
  }
]