{"id":"CVE-2026-99201","aliases":[],"title":"netlink: avoid hashing the network namespace pointer","titleSource":"Linux","descriptionSource":"Linux","products":[{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"078deff25f8a849ecd1c3fe17b1e473b1cf44f28","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"f88bb3606e4bd11ee035b682cddc2999e604609a","versionType":"git"}],"defaultStatus":"unaffected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99201"},{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","versionType":"semver"},{"version":"6.18.59","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"defaultStatus":"affected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99201"}],"remediation":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetlink: avoid hashing the network namespace pointer\n\nThe netlink rhashtable key includes a raw struct net pointer and a\nuser-controlled port ID. Both /proc/net/netlink and socket diagnostics\nexpose the table's bucket order. By binding and rebinding chosen\nNETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal\nbuckets and recover the low bits of the Jenkins hash. Its 32-bit seed\nand the limited set of kernel-image slides can then be searched offline\nto recover the address of init_net.\n\nUse the namespace's unique, non-address net_cookie in the comparison\nkey instead. It is assigned before the per-net initializers run and\nremains unchanged for the namespace's lifetime. The lookup key and\nobject hash are still built by netlink_compare_arg_init(), keeping\nlookup, insertion, removal and rehashing consistent while preserving\nnamespace separation. Neither public table walker needs to change.\n\nReading the socket's namespace cookie in netlink_compare() is safe\nunder RCU, including during namespace teardown. netlink_release()\nremoves the socket from the hash table and defers its final put with\ncall_rcu(). cleanup_net() runs the per-net exit methods and waits for\noutstanding RCU callbacks with rcu_barrier() before freeing namespace\nstorage.\n\nUnlike ns.ns_id, net_cookie is also available and initialized during\nsetup_net() in older stable kernels, making the change straightforward\nto backport to v5.15 and later.","severity":"unknown","score":null,"published":"2026-10-28T10:35:56.069Z","modified":"2026-10-28T10:35:56.069Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://git.kernel.org/stable/c/bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","https://git.kernel.org/stable/c/078deff25f8a849ecd1c3fe17b1e473b1cf44f28","https://git.kernel.org/stable/c/f88bb3606e4bd11ee035b682cddc2999e604609a"],"sources":[{"name":"CVE","id":"CVE-2026-99201","modified":"2026-10-28T10:35:56.069Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-99201"}],"assessments":[],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T19:55:31.817Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}