# CVE-2023-53365: ip6mr: Fix skb_under_panic in ip6mr_cache_report()

> A flaw in the Linux kernel's IPv6 multicast routing allows a local attacker to cause a system crash via a specific VLAN configuration.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 17 Sep 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2023-53365, DEBIAN-CVE-2023-53365, GHSA-29x7-qr43-qqmw, UBUNTU-CVE-2023-53365

## What is CVE-2023-53365?

CVE-2023-53365 is a medium-severity vulnerability in Linux kernel, published on 17 Sep 2025. 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:

ip6mr: Fix skb_under_panic in ip6mr_cache_report()

skbuff: skb_under_panic: text:ffffffff88771f69 len:56 put:-4
 head:ffff88805f86a800 data:ffff887f5f86a850 tail:0x88 end:0x2c0 dev:pim6reg
 ------------[ cut here ]------------
 kernel BUG at net/core/skbuff.c:192!
 invalid opcode: 0000 [#1] PREEMPT SMP KASAN
 CPU: 2 PID: 22968 Comm: kworker/2:11 Not tainted 6.5.0-rc3-00044-g0a8db05b571a #236
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
 Workqueue: ipv6_addrconf addrconf_dad_work
 RIP: 0010:skb_panic+0x152/0x1d0
 Call Trace:
  <TASK>
  skb_push+0xc4/0xe0
  ip6mr_cache_report+0xd69/0x19b0
  reg_vif_xmit+0x406/0x690
  dev_hard_start_xmit+0x17e/0x6e0
  __dev_queue_xmit+0x2d6a/0x3d20
  vlan_dev_hard_start_xmit+0x3ab/0x5c0
  dev_hard_start_xmit+0x17e/0x6e0
  __dev_queue_xmit+0x2d6a/0x3d20
  neigh_connected_output+0x3ed/0x570
  ip6_finish_output2+0x5b5/0x1950
  ip6_finish_output+0x693/0x11c0
  ip6_output+0x24b/0x880
  NF_HOOK.constprop.0+0xfd/0x530
  ndisc_send_skb+0x9db/0x1400
  ndisc_send_rs+0x12a/0x6c0
  addrconf_dad_completed+0x3c9/0xea0
  addrconf_dad_work+0x849/0x1420
  process_one_work+0xa22/0x16e0
  worker_thread+0x679/0x10c0
  ret_from_fork+0x28/0x60
  ret_from_fork_asm+0x11/0x20

When setup a vlan device on dev pim6reg, DAD ns packet may sent on reg_vif_xmit().
reg_vif_xmit()
    ip6mr_cache_report()
        skb_push(skb, -skb_network_offset(pkt));//skb_network_offset(pkt) is 4
And skb_push declared as:
	void *skb_push(struct sk_buff *skb, unsigned int len);
		skb->data -= len;
		//0xffff88805f86a84c - 0xfffffffc = 0xffff887f5f86a850
skb->data is set to 0xffff887f5f86a850, which is invalid mem addr, lead to skb_push() fails.

## Which versions are affected by CVE-2023-53365?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2023-53365?

Apply the vendor's patch.

## Is CVE-2023-53365 being exploited?

There is no known exploitation of CVE-2023-53365 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-2023-53365 and fix it if it is affected.

What it is: CVE-2023-53365 is a medium-severity vulnerability in Linux kernel, published on 17 Sep 2025. 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-2023-53365 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-2023-53365/ (Markdown: https://insights.sbomify.com/CVE-2023-53365/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53365
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53365
- OSV: https://osv.dev/vulnerability/CVE-2023-53365

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53365/
Summaries are generated and may contain mistakes; the official description above is the record.