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🛡️ CVE-2024-56558 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

nfsd: make sure exp active before svc_export_show

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

nfsd: make sure exp active before svc_export_show

The function e_show was called with protection from RCU. This only

ensures that exp will not be freed. Therefore, the reference count for

exp can drop to zero, which will trigger a refcount use-after-free

warning when exp_get is called. To resolve this issue, use

cache_get_rcu to ensure that exp remains active.

------------[ cut here ]------------

refcount_t: addition on 0; use-after-free.

WARNING: CPU: 3 PID: 819 at lib/refcount.c:25

refcount_warn_saturate+0xb1/0x120

CPU: 3 UID: 0 PID: 819 Comm: cat Not tainted 6.12.0-rc3+ #1

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS

1.16.1-2.fc37 04/01/2014

RIP: 0010:refcount_warn_saturate+0xb1/0x120

...

Call Trace:

<TASK>

e_show+0x20b/0x230 [nfsd]

seq_read_iter+0x589/0x770

seq_read+0x1e5/0x270

vfs_read+0x125/0x530

ksys_read+0xc1/0x160

do_syscall_64+0x5f/0x170

entry_SYSCALL_64_after_hwframe+0x76/0x7e

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 high, integrity high, 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:H/I:H/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: High — total loss, or loss the attacker controls.
  • Integrity impact: High — total loss, or loss the attacker controls.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

CVE-2024-56558 is recorded against 2 packages.

  • kernel (from 6.7.0 up to 6.12.4)
  • linux-kernel (from 6.7 up to 6.12.4)

Timeline and source

Published on 27 December 2024 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)
git.kernel.org (Web)
lists.debian.org (Web)
lists.debian.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-2024-56558 on other distributions

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

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2024-12-27
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.7.0 6.12.4
linux-kernel 6.7 6.12.4

References

Similar Threats

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