Linux Kernel up to 6.16.9 nexthop fib_lookup_good_nhc null pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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4.6$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, was found in Linux Kernel up to 6.16.9. Impacted is the function fib_lookup_good_nhc of the component nexthop. Such manipulation leads to null pointer dereference. This vulnerability is uniquely identified as CVE-2025-39980. No exploit exists. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.16.9. It has been rated as critical. Affected by this issue is the function fib_lookup_good_nhc of the component nexthop. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. CVE summarizes:

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: 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

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2025-39980 since 04/16/2025. The exploitation is known to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 274816 (Debian dsa-6053 : affs-modules-6.1.0-37-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.245, 5.15.194, 6.1.155, 6.6.109, 6.12.50 or 6.16.10 eliminates this vulnerability. Applying the patch e1e87ac0daacd51f522ecd1645cd76b5809303ed/0e7bfe7a268ccbd7859730c529161cafbf44637c/ec428fff792b7bd15b248dafca2e654b666b1304/24046d31f6f92220852d393d510b6062843e3fbd/f0e49fd13afe9dea7a09a1c9537fd00cea22badb/8dd4aa0122885f710930de135af2adc4ccc3238f/390b3a300d7872cef9588f003b204398be69ce08 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (274816) and CERT Bund (WID-SEC-2025-2298). Once again VulDB remains the best source for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel
  • IBM QRadar SIEM
  • Dell NetWorker

Productinfo

Type

Vendor

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.8
VulDB Meta Temp Score: 4.6

VulDB Base Score: 4.8
VulDB Temp Score: 4.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 274816
Nessus Name: Debian dsa-6053 : affs-modules-6.1.0-37-4kc-malta-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.245/5.15.194/6.1.155/6.6.109/6.12.50/6.16.10
Patch: e1e87ac0daacd51f522ecd1645cd76b5809303ed/0e7bfe7a268ccbd7859730c529161cafbf44637c/ec428fff792b7bd15b248dafca2e654b666b1304/24046d31f6f92220852d393d510b6062843e3fbd/f0e49fd13afe9dea7a09a1c9537fd00cea22badb/8dd4aa0122885f710930de135af2adc4ccc3238f/390b3a300d7872cef9588f003b204398be69ce08

Timelineinfo

04/16/2025 CVE reserved
10/15/2025 +182 days Advisory disclosed
10/15/2025 +0 days VulDB entry created
02/08/2026 +116 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-39980 (🔒)
GCVE (CVE): GCVE-0-2025-39980
GCVE (VulDB): GCVE-100-328652
CERT Bund: WID-SEC-2025-2298 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 10/15/2025 12:15
Updated: 02/08/2026 19:29
Changes: 10/15/2025 12:15 (59), 11/03/2025 15:31 (7), 11/12/2025 08:21 (2), 11/22/2025 16:50 (1), 12/21/2025 07:39 (1), 02/08/2026 19:29 (1)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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