CVE-2025-21716

CVE-2025-21716 is a medium-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix uninit-value in vxlan_vnifilter_dump() KMSAN reported an uninit-value access in vxlan_vnifilter_dump() [1]. If the length of the netlink message payload is less than sizeof(struct tunnel_msg), vxlan_vnifilter_dump() accesses bytes beyond the message. This can lead to uninit-value access. Fix this by returning an error in such situations. [1] BUG: KMSAN: uninit-value in vxlan_vnifilter_dump+0x328/0x920 drivers/net/vxlan/vxlan_vnifilter.c:422 vxlan_vnifilter_dump+0x328/0x920 drivers/net/vxlan/vxlan_vnifilter.c:422 rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6786 netlink_dump+0x93e/0x15f0 net/netlink/af_netlink.c:2317 __netlink_dump_start+0x716/0xd60 net/netlink/af_netlink.c:2432 netlink_dump_start include/linux/netlink.h:340 [inline] rtnetlink_dump_start net/core/rtnetlink.c:6815 [inline] rtnetlink_rcv_msg+0x1256/0x14a0 net/core/rtnetlink.c:6882 netlink_rcv_skb+0x467/0x660 net/netlink/af_netlink.c:2542 rtnetlink_rcv+0x35/0x40 net/core/rtnetlink.c:6944 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0xed6/0x1290 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x1092/0x1230 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:726 ____sys_sendmsg+0x7f4/0xb50 net/socket.c:2583 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2672 x64_sys_call+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xd9/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Uninit was created at: slab_post_alloc_hook mm/slub.c:4110 [inline] slab_alloc_node mm/slub.c:4153 [inline] kmem_cache_alloc_node_noprof+0x800/0xe80 mm/slub.c:4205 kmalloc_reserve+0x13b/0x4b0 net/core/skbuff.c:587 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:678 alloc_skb include/linux/skbuff.h:1323 [inline] netlink_alloc_large_skb+0xa5/0x280 net/netlink/af_netlink.c:1196 netlink_sendmsg+0xac9/0x1230 net/netlink/af_netlink.c:1866 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:726 ____sys_sendmsg+0x7f4/0xb50 net/socket.c:2583 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2672 x64_sys_call+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xd9/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f CPU: 0 UID: 0 PID: 30991 Comm: syz.4.10630 Not tainted 6.12.0-10694-gc44daa7e3c73 #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014

Frequently asked questions

What is CVE-2025-21716?
In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix uninit-value in vxlan_vnifilter_dump() KMSAN reported an uninit-value access in vxlan_vnifilter_dump() [1]. If the length of the netlink message payload is less than sizeof(struct tunnel_msg), vxlan_vnifilter_dump() accesses bytes beyond the message. This can lead to uninit-value access. Fix this by returning an error in such situations. [1] BUG: KMSAN: uninit-value in vxlan_vnifilter_dump+0x328/0x920 drivers/net/vxlan/vxlan_vnifilter.c:422 vxlan_vnifilter_dump+0x328/0x920 drivers/net/vxlan/vxlan_vnifilter.c:422 rtnl_dumpit+0xd5/0x2f0 net/core/rtnetlink.c:6786 netlink_dump+0x93e/0x15f0 net/netlink/af_netlink.c:2317 __netlink_dump_start+0x716/0xd60 net/netlink/af_netlink.c:2432 netlink_dump_start include/linux/netlink.h:340 [inline] rtnetlink_dump_start net/core/rtnetlink.c:6815 [inline] rtnetlink_rcv_msg+0x1256/0x14a0 net/core/rtnetlink.c:6882 netlink_rcv_skb+0x467/0x660 net/netlink/af_netlink.c:2542 rtnetlink_rcv+0x35/0x40 net/core/rtnetlink.c:6944 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0xed6/0x1290 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x1092/0x1230 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:726 ____sys_sendmsg+0x7f4/0xb50 net/socket.c:2583 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2672 x64_sys_call+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xd9/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Uninit was created at: slab_post_alloc_hook mm/slub.c:4110 [inline] slab_alloc_node mm/slub.c:4153 [inline] kmem_cache_alloc_node_noprof+0x800/0xe80 mm/slub.c:4205 kmalloc_reserve+0x13b/0x4b0 net/core/skbuff.c:587 __alloc_skb+0x347/0x7d0 net/core/skbuff.c:678 alloc_skb include/linux/skbuff.h:1323 [inline] netlink_alloc_large_skb+0xa5/0x280 net/netlink/af_netlink.c:1196 netlink_sendmsg+0xac9/0x1230 net/netlink/af_netlink.c:1866 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x330/0x3d0 net/socket.c:726 ____sys_sendmsg+0x7f4/0xb50 net/socket.c:2583 ___sys_sendmsg+0x271/0x3b0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x211/0x3e0 net/socket.c:2672 x64_sys_call+0x3878/0x3d90 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xd9/0x1d0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f CPU: 0 UID: 0 PID: 30991 Comm: syz.4.10630 Not tainted 6.12.0-10694-gc44daa7e3c73 #29 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014
How severe is CVE-2025-21716?
CVE-2025-21716 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-21716 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-21716?
CVE-2025-21716 affects Linux Linux Kernel. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2025-21716?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-21716 have an EU (EUVD) identifier?
Yes. CVE-2025-21716 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-5249.
When was CVE-2025-21716 published?
CVE-2025-21716 was published on 2025-02-27 and last updated on 2026-06-17.

References

Affected products (1)

More vulnerabilities in Linux Linux Kernel

All CVEs affecting Linux Linux Kernel →

Other CWE-908 (Use of Uninitialized Resource) vulnerabilities

Browse all CWE-908 (Use of Uninitialized Resource) vulnerabilities →