CVE-2025-71097

Description

In the Linux kernel, the following vulnerability has been resolved: ipv4: Fix reference count leak when using error routes with nexthop objects When a nexthop object is deleted, it is marked as dead and then fib_table_flush() is called to flush all the routes that are using the dead nexthop. The current logic in fib_table_flush() is to only flush error routes (e.g., blackhole) when it is called as part of network namespace dismantle (i.e., with flush_all=true). Therefore, error routes are not flushed when their nexthop object is deleted: # ip link add name dummy1 up type dummy # ip nexthop add id 1 dev dummy1 # ip route add 198.51.100.1/32 nhid 1 # ip route add blackhole 198.51.100.2/32 nhid 1 # ip nexthop del id 1 # ip route show blackhole 198.51.100.2 nhid 1 dev dummy1 As such, they keep holding a reference on the nexthop object which in turn holds a reference on the nexthop device, resulting in a reference count leak: # ip link del dev dummy1 [ 70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2 Fix by flushing error routes when their nexthop is marked as dead. IPv6 does not suffer from this problem.

Gravité et risque d'exploitation

CVE-2025-71097 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.14 %, ce qui la place devant 3.0 % des CVE référencées.

Que faire ?

• Vérifiez si Linux (versions 6.12.64, <=6.1.*, <=6.12.*, <5de7ad7e18356e39e8fbf7edd185a5faaf4f385a, 6.1.160, 493ced1ac47c48bb86d9d4e8e87df8592be85a0e, 0, 6.6.120, 5.15.198, <=5.10.*, <=6.6.*, 6.18.4, <ac782f4e3bfcde145b8a7f8af31d9422d94d172a, 5.3, <=6.18.*, <5.3, 5.10.248, <=*, <30386e090c49e803c0616a7147e43409c32a2b0e, <=5.15.*, <33ff5c207c873215e54e6176624ed57423cb7dea, 6.19, <5979338c83012110ccd45cae6517591770bfe536, <e3fc381320d04e4a74311e576a86cac49a16fc43, <ee4183501ea556dca31f5ffd8690aa9fd25b609f) est présent sur votre parc.
• Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
• À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
• Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

• https://git.kernel.org/stable/c/5de7ad7e18356e39e8fbf7edd185a5faaf4f385a
• https://git.kernel.org/stable/c/33ff5c207c873215e54e6176624ed57423cb7dea
• https://git.kernel.org/stable/c/30386e090c49e803c0616a7147e43409c32a2b0e
• https://git.kernel.org/stable/c/5979338c83012110ccd45cae6517591770bfe536
• https://git.kernel.org/stable/c/ee4183501ea556dca31f5ffd8690aa9fd25b609f
• https://git.kernel.org/stable/c/e3fc381320d04e4a74311e576a86cac49a16fc43
• https://git.kernel.org/stable/c/ac782f4e3bfcde145b8a7f8af31d9422d94d172a