vxlan: Fix NPD in {arp,neigh}_reduce() when using nexthop objects
In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix NPD in {arp,neigh}_reduce() when using nexthop objects When the "proxy" option is enabled on a VXLAN device, the device will suppress ARP requests and IPv6 Neighbor Solicitation messages if it is able to reply on behalf of the remote host. That is, if a matching and valid neighbor entry is configured on the VXLAN device whose MAC address is not behind the "any" remote (0.0.0.0 / ::). The code currently assumes that the FDB entry for the neighbor's MAC address points to a valid remote destination, but this is incorrect if the entry is associated with an FDB nexthop group. This can result in a NPD [1][3] which can be reproduced using [2][4]. Fix by checking that the remote destination exists before dereferencing it. [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] CPU: 4 UID: 0 PID: 365 Comm: arping Not tainted 6.17.0-rc2-virtme-g2a89cb21162c #2 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:vxlan_xmit+0xb58/0x15f0 [...] Call Trace: dev_hard_start_xmit+0x5d/0x1c0 __dev_queue_xmit+0x246/0xfd0 packet_sendmsg+0x113a/0x1850 __sock_sendmsg+0x38/0x70 __sys_sendto+0x126/0x180 __x64_sys_sendto+0x24/0x30 do_syscall_64+0xa4/0x260 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [2] #!/bin/bash ip address add 192.0.2.1/32 dev lo ip nexthop add id 1 via 192.0.2.2 fdb ip nexthop add id 10 group 1 fdb ip link add name vx0 up type v
CVE-2025-39850
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2025-39850
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "1274e1cc42264d4e629841e4f182795cb0becfd2",
"lessThan": "8ba034c41b20dc4f32ece748f1429709ae8ceedc",
"versionType": "git"
},
{
"status": "affected",
"version": "1274e1cc42264d4e629841e4f182795cb0becfd2",
"lessThan": "e211e3f4199ac829bd493632efcd131d337cba9d",
"versionType": "git"
},
{
"status": "affected",
"version": "1274e1cc42264d4e629841e4f182795cb0becfd2",
"lessThan": "8cfa0f076842f9b3b4eb52ae0e41d16e25cbf8fa",
"versionType": "git"
},
{
"status": "affected",
"version": "1274e1cc42264d4e629841e4f182795cb0becfd2",
"lessThan": "1f5d2fd1ca04a23c18b1bde9a43ce2fa2ffa1bce",
"versionType": "git"
}
],
"programFiles": [
"drivers/net/vxlan/vxlan_core.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.8"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.8",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.46",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.16.6",
"versionType": "semver",
"lessThanOrEqual": "6.16.*"
},
{
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"drivers/net/vxlan/vxlan_core.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-39850
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #46024 · Revision 1
- Added to Heist Feed
- Publisher date