rootpwn

high · CVSS v3 7.8

CVE-2026-98023

CVE-2026-98023 is a high‑severity vulnerability in the Linux kernel VXLAN driver that can corrupt the FDB list when dynamic entries referenc

Overview

CVE-2026-98023 is a high‑severity vulnerability in the Linux kernel VXLAN driver that can corrupt the FDB list when dynamic entries reference nexthops, potentially causing kernel crashes. The issue was fixed by rejecting such configurations. Defenders should apply the kernel patch to prevent this behavior.

Description

In the Linux kernel, the following vulnerability has been resolved: vxlan: reject dynamic fdb entries that reference a nexthop id The commit cited in the Fixes tag allowed VXLAN FDB entries to point to FDB nexthops so that overlay traffic could be load balanced across multiple VTEPs. Such entries can only be configured from user space, cannot be learned and cannot roam. They only make sense with a user space control plane such as E-VPN where data plane learning is disabled. Despite that, the VXLAN driver does not currently prevent such entries from being configured with the "dynamic" flag. The per-nexthop FDB list is only protected by the per-device hash lock, which is not sufficient when two VXLAN devices point to the same FDB nexthop and therefore share the list. Aging runs in softirq context without RTNL, so an entry deleted by one device can race with an addition or deletion from the other, leading to list corruption: list_del corruption. next->prev should be ffff8881069d9548, but was dead000000000122. (next=ffff8881069d9448) WARNING: CPU: 0 PID: 90 at lib/list_debug.c:65 __list_del_entry_valid_or_report+0x1aa/0x210 ... vxlan_fdb_destroy+0x5b8/0xad0 vxlan_cleanup+0x328/0x450 call_timer_fn+0x2a/0x1c0 run_timer_softirq+0x18c/0x210 BUG: KASAN: slab-use-after-free in vxlan_fdb_destroy Fix this by rejecting the bogus configuration of dynamic FDB entries that point to FDB nexthops, both when created and when an existing entry is updated. As such, the per-nexthop FDB list is only ever mutated under the RTNL lock. Add test cases to make sure that this does not regress in the future.

Impact

The vulnerability can lead to kernel memory corruption and system crashes, compromising integrity and availability for administrators and network operators running VXLAN overlays.

Remediation

Update the kernel to a version that includes the fix (e.g., 6.8+). Ensure VXLAN FDB entries are not configured with the dynamic flag pointing to nexthops. Monitor kernel logs for list_del corruption warnings.

Risk context

High severity (CVSS 7.8). No EPSS data available. Treat as high priority for systems using VXLAN.

Affected products

  • Linux kernel

Scores

Severity
high
CVSS v2
6.8
CVSS v3
7.8
CVSS v4
—
EPSS
—

linux kernel vxlan fdb list-corruption high-severity patch

← All CVEs

Related CVEs

high

CVE-2026-98026

This vulnerability affects the Linux kernel's bridge multicast handling. An improper RCU usage can lead to premature freeing of port group structures, potentially causing memory corruption or crashes. The fix converts mglist to RCU and corrects initialization order.

View analysis

high

CVE-2026-98101

In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source() pmc->sflist is read locklessly under rcu_read_lock() by inet6_mc_check() during packet reception in the UDP and RAW multicast receive paths. ip6_mc_source() mutated psl->sl_addr and psl->sl_count in-place when adding or removing a source filter. Additionally, when expanding the filter buffer, newpsl was published via rcu_assign_pointer() before writing the new source into the array. Because 16-byte struct in6_addr writes are not atomic and array shifting is not synchronized with RCU readers, concurrent readers in inet6_mc_check() could read torn IPv6 addresses or observe duplicated/missed source entries. Fix this by switching ip6_mc_source() to copy-on-write RCU updates: allocate and fully populate newpsl before publishing it via rcu_assign_pointer(), and reclaim the old filter via kfree_rcu(), matching ip6_mc_msfilter(). Also remove the now unused IP6_SFBLOCK macro.

View analysis

high

CVE-2026-97990

CVE-2026-97990 is a high‑severity flaw in the Linux kernel’s vdpa_sim_net driver that allows a negative TX pull result to be interpreted as a large positive length in the RX path. The bug can lead to memory corruption or denial of service when the kernel processes received packets. It was fixed by adding checks for non‑positive pull results before using the length.

View analysis

high

CVE-2026-97991

CVE-2026-97991 is a Linux kernel vulnerability affecting the vDPA block device driver. It allows out-of-range buffer offsets to be used in read/write operations, leading to potential memory corruption. The flaw can be triggered by VIRTIO_BLK_T_IN, VIRTIO_BLK_T_OUT, or VIRTIO_BLK_T_WRITE_ZEROES requests.

View analysis