{"api_version":"1","generated_at":"2026-07-23T06:03:52+00:00","cve":"CVE-2025-71097","urls":{"html":"https://cve.report/CVE-2025-71097","api":"https://cve.report/api/cve/CVE-2025-71097.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-71097","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-71097"},"summary":{"title":"ipv4: Fix reference count leak when using error routes with nexthop objects","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: Fix reference count leak when using error routes with nexthop objects\n\nWhen a nexthop object is deleted, it is marked as dead and then\nfib_table_flush() is called to flush all the routes that are using the\ndead nexthop.\n\nThe current logic in fib_table_flush() is to only flush error routes\n(e.g., blackhole) when it is called as part of network namespace\ndismantle (i.e., with flush_all=true). Therefore, error routes are not\nflushed when their nexthop object is deleted:\n\n # ip link add name dummy1 up type dummy\n # ip nexthop add id 1 dev dummy1\n # ip route add 198.51.100.1/32 nhid 1\n # ip route add blackhole 198.51.100.2/32 nhid 1\n # ip nexthop del id 1\n # ip route show\n blackhole 198.51.100.2 nhid 1 dev dummy1\n\nAs such, they keep holding a reference on the nexthop object which in\nturn holds a reference on the nexthop device, resulting in a reference\ncount leak:\n\n # ip link del dev dummy1\n [   70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2\n\nFix by flushing error routes when their nexthop is marked as dead.\n\nIPv6 does not suffer from this problem.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-01-13 16:16:09","updated_at":"2026-07-14 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the Linux kernel, the following vulnerability has been resolved:\n\nipv4: Fix reference count leak when using error routes with nexthop objects\n\nWhen a nexthop object is deleted, it is marked as dead and then\nfib_table_flush() is called to flush all the routes that are using the\ndead nexthop.\n\nThe current logic in fib_table_flush() is to only flush error routes\n(e.g., blackhole) when it is called as part of network namespace\ndismantle (i.e., with flush_all=true). Therefore, error routes are not\nflushed when their nexthop object is deleted:\n\n # ip link add name dummy1 up type dummy\n # ip nexthop add id 1 dev dummy1\n # ip route add 198.51.100.1/32 nhid 1\n # ip route add blackhole 198.51.100.2/32 nhid 1\n # ip nexthop del id 1\n # ip route show\n blackhole 198.51.100.2 nhid 1 dev dummy1\n\nAs such, they keep holding a reference on the nexthop object which in\nturn holds a reference on the nexthop device, resulting in a reference\ncount leak:\n\n # ip link del dev dummy1\n [   70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2\n\nFix by flushing error routes when their nexthop is marked as dead.\n\nIPv6 does not suffer from this problem."}],"providerMetadata":{"dateUpdated":"2026-05-11T21:54:41.289Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/5de7ad7e18356e39e8fbf7edd185a5faaf4f385a"},{"url":"https://git.kernel.org/stable/c/33ff5c207c873215e54e6176624ed57423cb7dea"},{"url":"https://git.kernel.org/stable/c/30386e090c49e803c0616a7147e43409c32a2b0e"},{"url":"https://git.kernel.org/stable/c/5979338c83012110ccd45cae6517591770bfe536"},{"url":"https://git.kernel.org/stable/c/ee4183501ea556dca31f5ffd8690aa9fd25b609f"},{"url":"https://git.kernel.org/stable/c/e3fc381320d04e4a74311e576a86cac49a16fc43"},{"url":"https://git.kernel.org/stable/c/ac782f4e3bfcde145b8a7f8af31d9422d94d172a"}],"title":"ipv4: Fix reference count leak when using error routes with nexthop 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Fix reference count leak when using error routes with next","CVE":"CVE-2025-71097","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"71097","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: Fix reference count leak when using error routes with nexthop objects\n\nWhen a nexthop object is deleted, it is marked as dead and then\nfib_table_flush() is called to flush all the routes that are using the\ndead nexthop.\n\nThe current logic in fib_table_flush() is to only flush error routes\n(e.g., blackhole) when it is called as part of network namespace\ndismantle (i.e., with flush_all=true). Therefore, error routes are not\nflushed when their nexthop object is deleted:\n\n # ip link add name dummy1 up type dummy\n # ip nexthop add id 1 dev dummy1\n # ip route add 198.51.100.1/32 nhid 1\n # ip route add blackhole 198.51.100.2/32 nhid 1\n # ip nexthop del id 1\n # ip route show\n blackhole 198.51.100.2 nhid 1 dev dummy1\n\nAs such, they keep holding a reference on the nexthop object which in\nturn holds a reference on the nexthop device, resulting in a reference\ncount leak:\n\n # ip link del dev dummy1\n [   70.516258] unregister_netdevice: waiting for dummy1 to become free. Usage count = 2\n\nFix by flushing error routes when their nexthop is marked as dead.\n\nIPv6 does not suffer from this problem.","Type":"Description","Title":"ipv4: Fix reference count leak when using error routes with next"}]}}}