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🛡️ CVE-2023-53291 — kernel

🟡 CVSS 5.5 — Medium ✅ No Known Exploit NVD
5.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale

In the Linux kernel, the following vulnerability has been resolved:

rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale

Running the 'kfree_rcu_test' test case [1] results in a splat [2].

The root cause is the kfree_scale_thread thread(s) continue running

after unloading the rcuscale module. This commit fixes that isue by

invoking kfree_scale_cleanup() from rcu_scale_cleanup() when removing

the rcuscale module.

[1] modprobe rcuscale kfree_rcu_test=1

// After some time

rmmod rcuscale

rmmod torture

[2] BUG: unable to handle page fault for address: ffffffffc0601a87

#PF: supervisor instruction fetch in kernel mode

#PF: error_code(0x0010) - not-present page

PGD 11de4f067 P4D 11de4f067 PUD 11de51067 PMD 112f4d067 PTE 0

Oops: 0010 [#1] PREEMPT SMP NOPTI

CPU: 1 PID: 1798 Comm: kfree_scale_thr Not tainted 6.3.0-rc1-rcu+ #1

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015

RIP: 0010:0xffffffffc0601a87

Code: Unable to access opcode bytes at 0xffffffffc0601a5d.

RSP: 0018:ffffb25bc2e57e18 EFLAGS: 00010297

RAX: 0000000000000000 RBX: ffffffffc061f0b6 RCX: 0000000000000000

RDX: 0000000000000000 RSI: ffffffff962fd0de RDI: ffffffff962fd0de

RBP: ffffb25bc2e57ea8 R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000

R13: 0000000000000000 R14: 000000000000000a R15: 00000000001c1dbe

FS: 0000000000000000(0000) GS:ffff921fa2200000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: ffffffffc0601a5d CR3: 000000011de4c006 CR4: 0000000000370ee0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Call Trace:

<TASK>

? kvfree_call_rcu+0xf0/0x3a0

? kthread+0xf3/0x120

? kthread_complete_and_exit+0x20/0x20

? ret_from_fork+0x1f/0x30

</TASK>

Modules linked in: rfkill sunrpc ... [last unloaded: torture]

CR2: ffffffffc0601a87

---[ end trace 0000000000000000 ]---

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2023-53291 is recorded against 2 packages.

  • kernel (from 6.4.0 up to 6.4.4)
  • linux-kernel (from 6.4 up to 6.4.4)

Timeline and source

Published on 16 September 2025 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

Other advisories for this package

kernel has other advisories on record. If you are patching this one, these are worth checking on the same host:

CVE-2023-53291 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Medium
CVSS Score 5.5
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2025-09-16
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.4.0 6.4.4
linux-kernel 6.4 6.4.4

Similar Threats

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