CVE-2025-21716 — vxlan: Fix uninit-value in vxlan_vnifilter_dump()
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
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+1
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux | ≥ f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and < cb1de9309a48cc5b771115781eec05075fd67039≥ f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and < a84d511165d6ba7f331b90ae6b6ce180ec534daa≥ f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and < f554bce488605d2f70e06eeab5e4d2448c813713≥ f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and < 1693d1fade71646a0731b6b213298cb443d186ea≥ f9c4bb0b245cee35ef66f75bf409c9573d934cf9 and < 5066293b9b7046a906eff60e3949a887ae185a43version 5.18 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel | ≥ 5.18 and < 6.1.129≥ 6.2 and < 6.6.76≥ 6.7 and < 6.12.13≥ 6.13 and < 6.13.2 | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 5.5 | CVSS 3.1 | Medium | 1.8 | 3.6 | nvd@nist.gov via NIST National Vulnerability Database |
| 5.5 | CVSS 3.1 | Medium | 1.8 | 3.6 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database |
| 5.5 | CVSS 3.1 | Medium | — | — | GitHub, Inc. via GitHub Security Advisories |
| 5.5 | CVSS 3.1 | Medium | — | — | CISA-ADP via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- SSVC assessment updated
- Record published
- Fix documented
- Affected products added · linux/linux kernel
- CVSS changed · 5.5
- Source status changed · → Modified
- Record created in this database
- 2025
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 14, 2026
- 1× Official description updated · Oct 14, 2026 – Oct 14, 2026
References
9 on the record
- git.kernel.org/stable/c/cb1de9309a48cc5b771115781eec05075fd67039
- git.kernel.org/stable/c/f554bce488605d2f70e06eeab5e4d2448c813713
- git.kernel.org/stable/c/5066293b9b7046a906eff60e3949a887ae185a43
- git.kernel.org/stable/c/a84d511165d6ba7f331b90ae6b6ce180ec534daa
- git.kernel.org/stable/c/1693d1fade71646a0731b6b213298cb443d186ea
- github.com/advisories/GHSA-89mr-qgjp-42xf
- cert-portal.siemens.com/productcert/html/ssa-784472.html
- nvd.nist.gov/vuln/detail/CVE-2025-21716
- lists.debian.org/debian-lts-announce/2025/03/msg00028.html
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
- Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
- Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
- Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
- Unknown CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2025-21716 is "vxlan: Fix uninit-value in vxlan_vnifilter_dump()", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.21% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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