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CVE-2025-37921— vxlan: vnifilter: Fix unlocked deletion of default FDB entry

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于vxlan模块在删除默认FDB条目时未加锁，可能导致数据竞争。

CVSS 7.8 · High EPSS 0.23% · P12

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux f9c4bb0b245cee35ef66f75bf409c9573d934cf9< 2d4a121296aa3940d2df9906f955c2b6b4e38bc3 affected
f9c4bb0b245cee35ef66f75bf409c9573d934cf9< 3576e9a80b6c4381b01ce0cbaa07f5e92d4492ed affected
f9c4bb0b245cee35ef66f75bf409c9573d934cf9< 5cb9e07f84e527974b12e82e2549fa6c0cc6eef0 affected
f9c4bb0b245cee35ef66f75bf409c9573d934cf9< 470206205588559e60035fceb5f256640cb45f99 affected
f9c4bb0b245cee35ef66f75bf409c9573d934cf9< 087a9eb9e5978e3ba362e1163691e41097e8ca20 affected
5.18 affected
< 5.18 unaffected
6.1.138≤ 6.1.* unaffected
… +4 more rows
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I. Basic Information for CVE-2025-37921

Vulnerability Information
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Vulnerability Title
vxlan: vnifilter: Fix unlocked deletion of default FDB entry
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: vxlan: vnifilter: Fix unlocked deletion of default FDB entry When a VNI is deleted from a VXLAN device in 'vnifilter' mode, the FDB entry associated with the default remote (assuming one was configured) is deleted without holding the hash lock. This is wrong and will result in a warning [1] being generated by the lockdep annotation that was added by commit ebe642067455 ("vxlan: Create wrappers for FDB lookup"). Reproducer: # ip link add vx0 up type vxlan dstport 4789 external vnifilter local 192.0.2.1 # bridge vni add vni 10010 remote 198.51.100.1 dev vx0 # bridge vni del vni 10010 dev vx0 Fix by acquiring the hash lock before the deletion and releasing it afterwards. Blame the original commit that introduced the issue rather than the one that exposed it. [1] WARNING: CPU: 3 PID: 392 at drivers/net/vxlan/vxlan_core.c:417 vxlan_find_mac+0x17f/0x1a0 [...] RIP: 0010:vxlan_find_mac+0x17f/0x1a0 [...] Call Trace: <TASK> __vxlan_fdb_delete+0xbe/0x560 vxlan_vni_delete_group+0x2ba/0x940 vxlan_vni_del.isra.0+0x15f/0x580 vxlan_process_vni_filter+0x38b/0x7b0 vxlan_vnifilter_process+0x3bb/0x510 rtnetlink_rcv_msg+0x2f7/0xb70 netlink_rcv_skb+0x131/0x360 netlink_unicast+0x426/0x710 netlink_sendmsg+0x75a/0xc20 __sock_sendmsg+0xc1/0x150 ____sys_sendmsg+0x5aa/0x7b0 ___sys_sendmsg+0xfc/0x180 __sys_sendmsg+0x121/0x1b0 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x4b/0x53
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
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于vxlan模块在删除默认FDB条目时未加锁，可能导致数据竞争。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux f9c4bb0b245cee35ef66f75bf409c9573d934cf9 ~ 2d4a121296aa3940d2df9906f955c2b6b4e38bc3 -
Linux Linux 5.18 -

II. Public POCs for CVE-2025-37921

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III. Intelligence Information for CVE-2025-37921

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Patches & Fixes for CVE-2025-37921 (2)

Same Patch Batch · Linux · 2025-05-20 · 95 CVEs total

CVE-2025-37894 9.8 CRITICAL net: use sock_gen_put() when sk_state is TCP_TIME_WAIT
CVE-2025-37924 9.8 CRITICAL ksmbd: fix use-after-free in kerberos authentication
CVE-2025-37935 9.8 CRITICAL net: ethernet: mtk_eth_soc: fix SER panic with 4GB+ RAM
CVE-2025-37959 9.4 CRITICAL bpf: Scrub packet on bpf_redirect_peer
CVE-2025-37926 8.8 HIGH ksmbd: fix use-after-free in ksmbd_session_rpc_open
CVE-2025-37899 8.8 HIGH ksmbd: fix use-after-free in session logoff
CVE-2025-37918 8.8 HIGH Bluetooth: btusb: avoid NULL pointer dereference in skb_dequeue()
CVE-2025-37944 8.8 HIGH wifi: ath12k: Fix invalid entry fetch in ath12k_dp_mon_srng_process
CVE-2025-37943 8.8 HIGH wifi: ath12k: Fix invalid data access in ath12k_dp_rx_h_undecap_nwifi
CVE-2025-37947 8.8 HIGH ksmbd: prevent out-of-bounds stream writes by validating *pos
CVE-2025-37952 8.8 HIGH ksmbd: Fix UAF in __close_file_table_ids
CVE-2025-37956 8.8 HIGH ksmbd: prevent rename with empty string
CVE-2025-37957 8.8 HIGH KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
CVE-2025-37936 8.7 HIGH perf/x86/intel: KVM: Mask PEBS_ENABLE loaded for guest with vCPU's value.
CVE-2025-37973 8.1 HIGH wifi: cfg80211: fix out-of-bounds access during multi-link element defragmentation
CVE-2025-37979 7.8 HIGH ASoC: qcom: Fix sc7280 lpass potential buffer overflow
CVE-2025-37901 7.8 HIGH irqchip/qcom-mpm: Prevent crash when trying to handle non-wake GPIOs
CVE-2025-37903 7.8 HIGH drm/amd/display: Fix slab-use-after-free in hdcp
CVE-2025-37923 7.8 HIGH tracing: Fix oob write in trace_seq_to_buffer()
CVE-2025-37920 7.8 HIGH xsk: Fix race condition in AF_XDP generic RX path

Showing top 20 of 95 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2025-37921

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