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CVE-2026-98023— vxlan: reject dynamic fdb entries that reference a nexthop id

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： vxlan：拒绝引用下一跳 ID 的动态 FDB 条目 Fixes 标签中引用的提交允许 VXLAN FDB（转发数据库）条目指向 FDB 下一跳，以便跨多个 VTEP（虚拟隧道端点）实现覆盖流量的负载均衡。此类条目只能从用户空间配置，无法通过学习获得，也不能漫游。它们仅在与用户空间控制平面（如 E-VPN，其中禁用了数据平面学习）配合使用时才有意义。 尽管如此，VXLAN 驱动程序目前并未阻止通过“动态”标志配置此类条目。每个下一跳的 FDB 列表仅受设备级哈希锁（per

CVSS 7.8 · High EPSS 0.12% · P2

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 1274e1cc42264d4e629841e4f182795cb0becfd2< 28f86eec851b7406a4bc6143f82aeba2882d9842 affected
1274e1cc42264d4e629841e4f182795cb0becfd2< 53359916ceb649b7e6947c8c2f669368a41c1354 affected
1274e1cc42264d4e629841e4f182795cb0becfd2< 3fa64d86fc64eda104e3e97721a12a42a2fd2073 affected
1274e1cc42264d4e629841e4f182795cb0becfd2< 98fc57d167446b95b4e719815fe79edef93f8e7a affected
5.8 affected
< 5.8 unaffected
6.12.111≤ 6.12.* unaffected
6.18.53≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-98023

Vulnerability Information
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Vulnerability Title
vxlan: reject dynamic fdb entries that reference a nexthop id
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 1274e1cc42264d4e629841e4f182795cb0becfd2 ~ 28f86eec851b7406a4bc6143f82aeba2882d9842 -
Linux Linux 5.8 -

II. Public POCs for CVE-2026-98023

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III. Intelligence Information for CVE-2026-98023

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Patches & Fixes for CVE-2026-98023 (4)

Same Patch Batch · Linux · 2026-09-25 · 372 CVEs total

CVE-2026-100075 9.8 CRITICAL RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters
CVE-2026-97555 8.8 HIGH smb: client: fix heap overflow in DACL owner/group rewrite
CVE-2026-97957 8.8 HIGH net: hinic: fix mailbox segment buffer overflow
CVE-2026-97527 8.8 HIGH scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock
CVE-2026-97528 8.8 HIGH scsi: qla2xxx: Unlink NVMe unsol ctx before freeing on LS reject error
CVE-2026-98115 8.8 HIGH ksmbd: safely drain sessions during logoff
CVE-2026-97525 8.2 HIGH x86/mm/pat: Allocate split page tables as kernel page tables
CVE-2026-98070 8.1 HIGH net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()
CVE-2026-97573 8.1 HIGH bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
CVE-2026-97570 8.1 HIGH bnxt_en: Bound SW TPA IDs to prevent crashes
CVE-2026-98069 8.1 HIGH net/rds: acquire the fastpath locks in rds_conn_shutdown()
CVE-2026-98130 8.1 HIGH sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START
CVE-2026-98122 7.8 HIGH vxlan: mdb: Fix use-after-free in vxlan_mdb_remote_src_del()
CVE-2026-97576 7.8 HIGH media: v4l2-ctrls: validate HEVC tile counts
CVE-2026-98112 7.8 HIGH ksmbd: fix listener task lifetime on netdev events
CVE-2026-98002 7.8 HIGH iommu/amd: Fix ineffective error check in nested domain allocation
CVE-2026-97937 7.8 HIGH ftrace: fork: Initialize function graph state before copy_exec_state()
CVE-2026-97940 7.8 HIGH ipv6: fix fib6 walker UAF on seq stop
CVE-2026-98116 7.8 HIGH ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF
CVE-2026-97578 7.8 HIGH media: verisilicon: rockchip: guard VPU981 AV1 divisor and tile buffer

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98023

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