{"id":"CVE-2026-99201","title":"netlink: avoid hashing the network namespace pointer","summary":"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…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < 078deff25f8a849ecd1c3fe17b1e473b1cf44f28","Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < f88bb3606e4bd11ee035b682cddc2999e604609a","Linux 4.1"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:35:56.069Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99201","references":[{"url":"https://git.kernel.org/stable/c/bdd55b8a8acbf6b4840ab420eb6a63774bf4593b"},{"url":"https://git.kernel.org/stable/c/078deff25f8a849ecd1c3fe17b1e473b1cf44f28"},{"url":"https://git.kernel.org/stable/c/f88bb3606e4bd11ee035b682cddc2999e604609a"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.364Z","slug":"CVE-2026-99201","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < bdd55b8a8acbf6b4840ab420eb6a63774bf4593b`\n- `Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < 078deff25f8a849ecd1c3fe17b1e473b1cf44f28`\n- `Linux >= c428ecd1a21f1457ca3beb4df71b8a079c410e41 < f88bb3606e4bd11ee035b682cddc2999e604609a`\n- `Linux 4.1`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}