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NVD / CVE Program· CNA Linux

CVE-2025-68801: mlxsw: spectrum_router: Fix neighbour use-after-free

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 4a3c569005f42ab5e5b2ad637132a33bf102cc08, 675c5aeadf6472672c472dc0f26401e4fcfbf254, 8b0e69763ef948fb872a7767df4be665d18f5fd4; azl3 kernel 6.6.119.3-3 on Azure Linux 3.0 6.6.121.1-1.

Low priority for now. Upgrade to Linux Linux 4a3c569005f42ab5e5b2ad637132a33bf102cc08, 675c5aeadf6472672c472dc0f26401e4fcfbf254, 8b0e69763ef948fb872a7767df4be665d18f5fd4; azl3 kernel 6.6.119.3-3 on Azure Linux 3.0 6.6.121.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_router: Fix neighbour use-after-free We sometimes observe use-after-free when dereferencing a neighbour [1]. The problem seems to be that the driver stores a pointer to the neighbour, but without holding a reference on it. A reference is only taken when the neighbour is used by a nexthop. Fix by simplifying the reference counting scheme. Always take a reference when storing a neighbour pointer in a neighbour entry. Avoid taking a referencing when the neighbour is used by a nexthop as the neighbour entry associated with the nexthop already holds a reference. Tested by running the test that uncovered the problem over 300 times. Without this patch the problem was reproduced after a handful of iterations. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_neigh_entry_update+0x2d4/0x310 Read of size 8 at addr ffff88817f8e3420 by task ip/3929 CPU: 3 UID: 0 PID: 3929 Comm: ip Not tainted 6.18.0-rc4-virtme-g36b21a067510 #3 PREEMPT(full) Hardware name: Nvidia SN5600/VMOD0013, BIOS 5.13 05/31/2023 Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_address_description.constprop.0+0x6e/0x300 print_report+0xfc/0x1fb kasan_report+0xe4/0x110 mlxsw_sp_neigh_entry_update+0x2d4/0x310 mlxsw_sp_router_rif_gone_sync+0x35f/0x510 mlxsw_sp_rif_destroy+0x1ea/0x730 mlxsw_sp_inetaddr_port_vlan_event+0xa1/0x1b0 __mlxsw_sp_inetaddr_lag_event+0xcc/0x130 __mlxsw_sp_inetaddr_event+0xf5/0x3c0 mlxsw_sp_router_netdevice_event+0x1015/0x1580 notifier_call_chain+0xcc/0x150 call_netdevice_notifiers_info+0x7e/0x100 __netdev_upper_dev_unlink+0x10b/0x210 netdev_upper_dev_unlink+0x79/0xa0 vrf_del_slave+0x18/0x50 do_set_master+0x146/0x7d0 do_setlink.isra.0+0x9a0/0x2880 rtnl_newlink+0x637/0xb20 rtnetlink_rcv_msg+0x6fe/0xb90 netlink_rcv_skb+0x123/0x380 netlink_unicast+0x4a3/0x770 netlink_sendmsg+0x75b/0xc90 __sock_sendmsg+0xbe/0x160 ____sys_sendmsg+0x5b2/0x7d0 ___sys_sendmsg+0xfd/0x180 __sys_sendmsg+0x124/0x1c0 do_syscall_64+0xbb/0xfd0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [...] Allocated by task 109: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x7b/0x90 __kmalloc_noprof+0x2c1/0x790 neigh_alloc+0x6af/0x8f0 ___neigh_create+0x63/0xe90 mlxsw_sp_nexthop_neigh_init+0x430/0x7e0 mlxsw_sp_nexthop_type_init+0x212/0x960 mlxsw_sp_nexthop6_group_info_init.constprop.0+0x81f/0x1280 mlxsw_sp_nexthop6_group_get+0x392/0x6a0 mlxsw_sp_fib6_entry_create+0x46a/0xfd0 mlxsw_sp_router_fib6_replace+0x1ed/0x5f0 mlxsw_sp_router_fib6_event_work+0x10a/0x2a0 process_one_work+0xd57/0x1390 worker_thread+0x4d6/0xd40 kthread+0x355/0x5b0 ret_from_fork+0x1d4/0x270 ret_from_fork_asm+0x11/0x20 Freed by task 154: kasan_save_stack+0x30/0x50 kasan_save_track+0x14/0x30 __kasan_save_free_info+0x3b/0x60 __kasan_slab_free+0x43/0x70 kmem_cache_free_bulk.part.0+0x1eb/0x5e0 kvfree_rcu_bulk+0x1f2/0x260 kfree_rcu_work+0x130/0x1b0 process_one_work+0xd57/0x1390 worker_thread+0x4d6/0xd40 kthread+0x355/0x5b0 ret_from_fork+0x1d4/0x270 ret_from_fork_asm+0x11/0x20 Last potentially related work creation: kasan_save_stack+0x30/0x50 kasan_record_aux_stack+0x8c/0xa0 kvfree_call_rcu+0x93/0x5b0 mlxsw_sp_router_neigh_event_work+0x67d/0x860 process_one_work+0xd57/0x1390 worker_thread+0x4d6/0xd40 kthread+0x355/0x5b0 ret_from_fork+0x1d4/0x270 ret_from_fork_asm+0x11/0x20

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Jan 13, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2025-68801

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 4.8affected
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before a2dfe6758fc63e542105bee8b17a3a7485684db0affected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before 9e0a0d9eeb0dbeba2c83fa837885b19b8b9230fcaffected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before c437fbfd4382412598cdda1f8e2881b523668cc2affected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before 4a3c569005f42ab5e5b2ad637132a33bf102cc08affected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before ed8141b206bdcfd5d0b92c90832eeb77b7a60a0aaffected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before 675c5aeadf6472672c472dc0f26401e4fcfbf254affected · git
    • 6cf3c971dc84cb36579515ddb488919b9e9fb6de and later · before 8b0e69763ef948fb872a7767df4be665d18f5fd4affected · git
    • before 4.8not affected · semver
    • 5.10.248 and later · up to and including 5.10.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.162-16.1.162-1
Debian:13linuxbefore 6.12.69-16.12.69-1
Debian:14linuxbefore 6.18.3-16.18.3-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2025-68798Jan 13, 2026 · perf/x86/amd: Check event before enable to avoid GPF
    0Monitor
  • ← EarlierCVE-2025-68800Jan 13, 2026 · mlxsw: spectrum_mr: Fix use-after-free when updating multicast route stats
    31Monitor
  • Later →CVE-2025-68803Jan 13, 2026 · NFSD: NFSv4 file creation neglects setting ACL
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux4a3c569005f42ab5e5b2ad637132a33bf102cc08Vendor (CNA)
Linux Linux675c5aeadf6472672c472dc0f26401e4fcfbf254Vendor (CNA)
Linux Linux8b0e69763ef948fb872a7767df4be665d18f5fd4Vendor (CNA)
Linux Linux9e0a0d9eeb0dbeba2c83fa837885b19b8b9230fcVendor (CNA)
Linux Linuxa2dfe6758fc63e542105bee8b17a3a7485684db0Vendor (CNA)
Linux Linuxc437fbfd4382412598cdda1f8e2881b523668cc2Vendor (CNA)
Linux Linuxed8141b206bdcfd5d0b92c90832eeb77b7a60a0aVendor (CNA)
azl3 kernel 6.6.119.3-3 on Azure Linux 3.06.6.121.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.162-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-63979187 days apartnet/handshake: hand off the pinned file reference to accept_doit
    39Monitor
  • CVE-2026-64523193 days apartnet/handshake: Take a long-lived file reference at submit
    39Monitor
  • CVE-2026-64530194 days apartnet/sched: cls_api: Handle TC_ACT_CONSUMED in tcf_qevent_handle
    39Monitor
  • CVE-2026-64541195 days apartnet/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
    39Monitor
  • CVE-2026-64564203 days apartsctp: don't free the ASCONF's own transport in DEL-IP processing
    39Monitor
  • CVE-2026-68381209 days apartksmbd: pin conn during async oplock break notification
    39Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

c
free(dev->buf);/* ... another thread is still running ... */process(dev->buf);

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records