nexthop: Forbid FDB status change while nexthop is in a group
Summary
| CVE | CVE-2025-39980 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2025-10-15 08:15:35 UTC |
| Updated | 2026-07-14 13:17:52 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: nexthop: Forbid FDB status change while nexthop is in a group The kernel forbids the creation of non-FDB nexthop groups with FDB nexthops: # ip nexthop add id 1 via 192.0.2.1 fdb # ip nexthop add id 2 group 1 Error: Non FDB nexthop group cannot have fdb nexthops. And vice versa: # ip nexthop add id 3 via 192.0.2.2 dev dummy1 # ip nexthop add id 4 group 3 fdb Error: FDB nexthop group can only have fdb nexthops. However, as long as no routes are pointing to a non-FDB nexthop group, the kernel allows changing the type of a nexthop from FDB to non-FDB and vice versa: # ip nexthop add id 5 via 192.0.2.2 dev dummy1 # ip nexthop add id 6 group 5 # ip nexthop replace id 5 via 192.0.2.2 fdb # echo $? 0 This configuration is invalid and can result in a NPD [1] since FDB nexthops are not associated with a nexthop device: # ip route add 198.51.100.1/32 nhid 6 # ping 198.51.100.1 Fix by preventing nexthop FDB status change while the nexthop is in a group: # ip nexthop add id 7 via 192.0.2.2 dev dummy1 # ip nexthop add id 8 group 7 # ip nexthop replace id 7 via 192.0.2.2 fdb Error: Cannot change nexthop FDB status while in a group. [1] BUG: kernel NULL pointer dereference, address: 00000000000003c0 [...] Oops: Oops: 0000 [#1] SMP CPU: 6 UID: 0 PID: 367 Comm: ping Not tainted 6.17.0-rc6-virtme-gb65678cacc03 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:fib_lookup_good_nhc+0x1e/0x80 [...] Call Trace: <TASK> fib_table_lookup+0x541/0x650 ip_route_output_key_hash_rcu+0x2ea/0x970 ip_route_output_key_hash+0x55/0x80 __ip4_datagram_connect+0x250/0x330 udp_connect+0x2b/0x60 __sys_connect+0x9c/0xd0 __x64_sys_connect+0x18/0x20 do_syscall_64+0xa4/0x2a0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 |
Risk And Classification
EPSS: 0.001930000 probability, percentile 0.090880000 (date 2026-07-14)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 e1e87ac0daacd51f522ecd1645cd76b5809303ed git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 0e7bfe7a268ccbd7859730c529161cafbf44637c git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 ec428fff792b7bd15b248dafca2e654b666b1304 git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 24046d31f6f92220852d393d510b6062843e3fbd git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 f0e49fd13afe9dea7a09a1c9537fd00cea22badb git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 8dd4aa0122885f710930de135af2adc4ccc3238f git | Not specified |
| CNA | Linux | Linux | affected 38428d68719c454d269cb03b776d8a4b0ad66111 390b3a300d7872cef9588f003b204398be69ce08 git | Not specified |
| CNA | Linux | Linux | affected 5.8 | Not specified |
| CNA | Linux | Linux | unaffected 5.8 semver | Not specified |
| CNA | Linux | Linux | unaffected 5.10.245 5.10.* semver | Not specified |
| CNA | Linux | Linux | unaffected 5.15.194 5.15.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.155 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.109 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.50 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.16.10 6.16.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.17 * original_commit_for_fix | Not specified |
| ADP | Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | affected V3.1.6 * custom | Not specified |
| ADP | Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP | affected V3.1.6 * custom | Not specified |
| ADP | Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | affected V3.1.6 * custom | Not specified |
| ADP | Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP | affected V3.1.6 * custom | Not specified |
| ADP | Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP | affected V3.1.6 * custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/ec428fff792b7bd15b248dafca2e654b666b1304 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/24046d31f6f92220852d393d510b6062843e3fbd | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/8dd4aa0122885f710930de135af2adc4ccc3238f | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e1e87ac0daacd51f522ecd1645cd76b5809303ed | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/390b3a300d7872cef9588f003b204398be69ce08 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| cert-portal.siemens.com/productcert/html/ssa-019113.html | 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e | cert-portal.siemens.com | |
| git.kernel.org/stable/c/f0e49fd13afe9dea7a09a1c9537fd00cea22badb | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/0e7bfe7a268ccbd7859730c529161cafbf44637c | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.