CVE-2025-37921
What it is
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
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of data exposure, data tampering, service disruption.
- Exploit odds
- 0.2% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.2% in the next 30 days (EPSS).
- Severity: 7.8 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.2% · EPSS, next 30 days
- Record status
- Modified
Affected
- Linux Kernel < 6.1.138
- Linux Kernel < 6.6.90
- Linux Kernel < 6.12.28
- Linux Kernel < 6.14.6
- Linux Kernel 6.15
- Debian Linux 11.0
Attack profile CVSS 3.1 · 7.8
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2025-37921.md and follow it. Check whether this project is affected by CVE-2025-37921. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/087a9eb9e5978e3ba362e1163691e41097e8ca20
- https://git.kernel.org/stable/c/2d4a121296aa3940d2df9906f955c2b6b4e38bc3
- https://git.kernel.org/stable/c/3576e9a80b6c4381b01ce0cbaa07f5e92d4492ed
- https://git.kernel.org/stable/c/470206205588559e60035fceb5f256640cb45f99
- https://git.kernel.org/stable/c/5cb9e07f84e527974b12e82e2549fa6c0cc6eef0
References
- https://git.kernel.org/stable/c/087a9eb9e5978e3ba362e1163691e41097e8ca20
- https://git.kernel.org/stable/c/2d4a121296aa3940d2df9906f955c2b6b4e38bc3
- https://git.kernel.org/stable/c/3576e9a80b6c4381b01ce0cbaa07f5e92d4492ed
- https://git.kernel.org/stable/c/470206205588559e60035fceb5f256640cb45f99
- https://git.kernel.org/stable/c/5cb9e07f84e527974b12e82e2549fa6c0cc6eef0
- https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html