# CVE-2024-56658: net: defer final 'struct net' free in netns dismantle

> A use-after-free in the Linux kernel network namespace teardown allows attackers to cause a system crash or potentially execute arbitrary code.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Dec 2024
- **Updated:** 5 Aug 2026
- **Also known as:** AZL-54798, AZL-54871, BELL-CVE-2024-56658, DEBIAN-CVE-2024-56658, GHSA-23x6-w5q4-2mqw, UBUNTU-CVE-2024-56658

## What is CVE-2024-56658?

CVE-2024-56658 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

net: defer final 'struct net' free in netns dismantle

Ilya reported a slab-use-after-free in dst_destroy [1]

Issue is in xfrm6_net_init() and xfrm4_net_init() :

They copy xfrm[46]_dst_ops_template into net->xfrm.xfrm[46]_dst_ops.

But net structure might be freed before all the dst callbacks are
called. So when dst_destroy() calls later :

if (dst->ops->destroy)
    dst->ops->destroy(dst);

dst->ops points to the old net->xfrm.xfrm[46]_dst_ops, which has been freed.

See a relevant issue fixed in :

ac888d58869b ("net: do not delay dst_entries_add() in dst_release()")

A fix is to queue the 'struct net' to be freed after one
another cleanup_net() round (and existing rcu_barrier())

[1]

BUG: KASAN: slab-use-after-free in dst_destroy (net/core/dst.c:112)
Read of size 8 at addr ffff8882137ccab0 by task swapper/37/0
Dec 03 05:46:18 kernel:
CPU: 37 UID: 0 PID: 0 Comm: swapper/37 Kdump: loaded Not tainted 6.12.0 #67
Hardware name: Red Hat KVM/RHEL, BIOS 1.16.1-1.el9 04/01/2014
Call Trace:
 <IRQ>
dump_stack_lvl (lib/dump_stack.c:124)
print_address_description.constprop.0 (mm/kasan/report.c:378)
? dst_destroy (net/core/dst.c:112)
print_report (mm/kasan/report.c:489)
? dst_destroy (net/core/dst.c:112)
? kasan_addr_to_slab (mm/kasan/common.c:37)
kasan_report (mm/kasan/report.c:603)
? dst_destroy (net/core/dst.c:112)
? rcu_do_batch (kernel/rcu/tree.c:2567)
dst_destroy (net/core/dst.c:112)
rcu_do_batch (kernel/rcu/tree.c:2567)
? __pfx_rcu_do_batch (kernel/rcu/tree.c:2491)
? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4339 kernel/locking/lockdep.c:4406)
rcu_core (kernel/rcu/tree.c:2825)
handle_softirqs (kernel/softirq.c:554)
__irq_exit_rcu (kernel/softirq.c:589 kernel/softirq.c:428 kernel/softirq.c:637)
irq_exit_rcu (kernel/softirq.c:651)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1049 arch/x86/kernel/apic/apic.c:1049)
 </IRQ>
 <TASK>
asm_sysvec_apic_timer_interrupt (./arch/x86/include/asm/idtentry.h:702)
RIP: 0010:default_idle (./arch/x86/include/asm/irqflags.h:37 ./arch/x86/include/asm/irqflags.h:92 arch/x86/kernel/process.c:743)
Code: 00 4d 29 c8 4c 01 c7 4c 29 c2 e9 6e ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 90 0f 00 2d c7 c9 27 00 fb f4 <fa> c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90
RSP: 0018:ffff888100d2fe00 EFLAGS: 00000246
RAX: 00000000001870ed RBX: 1ffff110201a5fc2 RCX: ffffffffb61a3e46
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffffb3d4d123
RBP: 0000000000000000 R08: 0000000000000001 R09: ffffed11c7e1835d
R10: ffff888e3f0c1aeb R11: 0000000000000000 R12: 0000000000000000
R13: ffff888100d20000 R14: dffffc0000000000 R15: 0000000000000000
? ct_kernel_exit.constprop.0 (kernel/context_tracking.c:148)
? cpuidle_idle_call (kernel/sched/idle.c:186)
default_idle_call (./include/linux/cpuidle.h:143 kernel/sched/idle.c:118)
cpuidle_idle_call (kernel/sched/idle.c:186)
? __pfx_cpuidle_idle_call (kernel/sched/idle.c:168)
? lock_release (kernel/locking/lockdep.c:467 kernel/locking/lockdep.c:5848)
? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4347 kernel/locking/lockdep.c:4406)
? tsc_verify_tsc_adjust (arch/x86/kernel/tsc_sync.c:59)
do_idle (kernel/sched/idle.c:326)
cpu_startup_entry (kernel/sched/idle.c:423 (discriminator 1))
start_secondary (arch/x86/kernel/smpboot.c:202 arch/x86/kernel/smpboot.c:282)
? __pfx_start_secondary (arch/x86/kernel/smpboot.c:232)
? soft_restart_cpu (arch/x86/kernel/head_64.S:452)
common_startup_64 (arch/x86/kernel/head_64.S:414)
 </TASK>
Dec 03 05:46:18 kernel:
Allocated by task 12184:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (./arch/x86/include/asm/current.h:49 mm/kasan/common.c:60 mm/kasan/common.c:69)
__kasan_slab_alloc (mm/kasan/common.c:319 mm/kasan/common.c:345)
kmem_cache_alloc_noprof (mm/slub.c:4085 mm/slub.c:4134 mm/slub.c:4141)
copy_net_ns (net/core/net_namespace.c:421 net/core/net_namespace.c:480)
create_new_namespaces
---truncated---

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2024-56658?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56658?

Apply the vendor's patch.

## Is CVE-2024-56658 being exploited?

There is no known exploitation of CVE-2024-56658 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-56658 and fix it if it is affected.

What it is: CVE-2024-56658 is a high-severity use after free vulnerability in Linux kernel, published on 27 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-56658 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-56658/ (Markdown: https://insights.sbomify.com/CVE-2024-56658/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56658
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56658
- OSV: https://osv.dev/vulnerability/CVE-2024-56658

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56658/
Summaries are generated and may contain mistakes; the official description above is the record.