CVE-2025-71097 (GCVE-0-2025-71097)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:34 – Updated: 2026-01-13 15:34
VLAI?
Title
ipv4: Fix reference count leak when using error routes with nexthop objects
Summary
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 493ced1ac47c48bb86d9d4e8e87df8592be85a0e , < 30386e090c49e803c0616a7147e43409c32a2b0e (git)
Affected: 493ced1ac47c48bb86d9d4e8e87df8592be85a0e , < 5979338c83012110ccd45cae6517591770bfe536 (git)
Affected: 493ced1ac47c48bb86d9d4e8e87df8592be85a0e , < ee4183501ea556dca31f5ffd8690aa9fd25b609f (git)
Affected: 493ced1ac47c48bb86d9d4e8e87df8592be85a0e , < e3fc381320d04e4a74311e576a86cac49a16fc43 (git)
Affected: 493ced1ac47c48bb86d9d4e8e87df8592be85a0e , < ac782f4e3bfcde145b8a7f8af31d9422d94d172a (git)
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    Linux Linux Affected: 5.3
Unaffected: 0 , < 5.3 (semver)
Unaffected: 6.1.160 , ≤ 6.1.* (semver)
Unaffected: 6.6.120 , ≤ 6.6.* (semver)
Unaffected: 6.12.64 , ≤ 6.12.* (semver)
Unaffected: 6.18.4 , ≤ 6.18.* (semver)
Unaffected: 6.19-rc4 , ≤ * (original_commit_for_fix)
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          "lang": "en",
          "value": "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."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-01-13T15:34:56.814Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/30386e090c49e803c0616a7147e43409c32a2b0e"
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          "url": "https://git.kernel.org/stable/c/5979338c83012110ccd45cae6517591770bfe536"
        },
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        },
        {
          "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 objects",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-71097",
    "datePublished": "2026-01-13T15:34:56.814Z",
    "dateReserved": "2026-01-13T15:30:19.650Z",
    "dateUpdated": "2026-01-13T15:34:56.814Z",
    "state": "PUBLISHED"
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  }
}


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