# CVE-2025-68800: mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats

> A use-after-free vulnerability in the Linux kernel mlxsw driver allows attackers to cause denial of service or potentially execute code via multicast route updates.

- **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:** 13 Jan 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-74378, BELL-CVE-2025-68800, DEBIAN-CVE-2025-68800, GHSA-jhc9-chhp-3xfj, ROOT-OS-DEBIAN-11-CVE-2025-68800, ROOT-OS-DEBIAN-12-CVE-2025-68800, ROOT-OS-DEBIAN-13-CVE-2025-68800, ROOT-OS-UBUNTU-2204-CVE-2025-68800, ROOT-OS-UBUNTU-2404-CVE-2025-68800, UBUNTU-CVE-2025-68800

## What is CVE-2025-68800?

CVE-2025-68800 is a high-severity use after free vulnerability in Linux, published on 13 Jan 2026. 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:

mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats

Cited commit added a dedicated mutex (instead of RTNL) to protect the
multicast route list, so that it will not change while the driver
periodically traverses it in order to update the kernel about multicast
route stats that were queried from the device.

One instance of list entry deletion (during route replace) was missed
and it can result in a use-after-free [1].

Fix by acquiring the mutex before deleting the entry from the list and
releasing it afterwards.

[1]
BUG: KASAN: slab-use-after-free in mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
Read of size 8 at addr ffff8881523c2fa8 by task kworker/2:5/22043

CPU: 2 UID: 0 PID: 22043 Comm: kworker/2:5 Not tainted 6.18.0-rc1-custom-g1a3d6d7cd014 #1 PREEMPT(full)
Hardware name: Mellanox Technologies Ltd. MSN2010/SA002610, BIOS 5.6.5 08/24/2017
Workqueue: mlxsw_core mlxsw_sp_mr_stats_update [mlxsw_spectrum]
Call Trace:
 <TASK>
 dump_stack_lvl+0xba/0x110
 print_report+0x174/0x4f5
 kasan_report+0xdf/0x110
 mlxsw_sp_mr_stats_update+0x4a5/0x540 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:1006 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 29933:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_kmalloc+0x8f/0xa0
 mlxsw_sp_mr_route_add+0xd8/0x4770 [mlxsw_spectrum]
 mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30

Freed by task 29933:
 kasan_save_stack+0x30/0x50
 kasan_save_track+0x14/0x30
 __kasan_save_free_info+0x3b/0x70
 __kasan_slab_free+0x43/0x70
 kfree+0x14e/0x700
 mlxsw_sp_mr_route_add+0x2dea/0x4770 drivers/net/ethernet/mellanox/mlxsw/spectrum_mr.c:444 [mlxsw_spectrum]
 mlxsw_sp_router_fibmr_event_work+0x371/0xad0 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c:7965 [mlxsw_spectrum]
 process_one_work+0x9cc/0x18e0
 worker_thread+0x5df/0xe40
 kthread+0x3b8/0x730
 ret_from_fork+0x3e9/0x560
 ret_from_fork_asm+0x1a/0x30

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-68800?


## How do I fix CVE-2025-68800?

Apply the vendor's patch.

## Is CVE-2025-68800 being exploited?

There is no known exploitation of CVE-2025-68800 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68800 and fix it if it is affected.

What it is: CVE-2025-68800 is a high-severity use after free vulnerability in Linux, published on 13 Jan 2026. 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-2025-68800 in the wild and no public exploit code.

Affected product: Linux. 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-2025-68800/ (Markdown: https://insights.sbomify.com/CVE-2025-68800/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68800
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68800
- OSV: https://osv.dev/vulnerability/CVE-2025-68800

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68800/
Summaries are generated and may contain mistakes; the official description above is the record.