{"id":"CVE-2026-99201","state":"PUBLISHED","title":"netlink: avoid hashing the network namespace pointer","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.","publishedAt":"2026-10-28T10:35:56.069Z","updatedAt":"2026-10-30T12:42:51.128Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"c61431f3b8c9824e9848a0308054f92b27fa7794","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"f8d2690f3c5dfad1fc306f6d5d84a1d3176c3af9","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"c03fb9c4be3b2dd0996d91e54f65407f7f475238","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"41a2f69f091b0765f17890d8ac04852c12f25cf6","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"18edcb9945118beb7a1b64a31a7370ecab485a79","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"078deff25f8a849ecd1c3fe17b1e473b1cf44f28","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"f88bb3606e4bd11ee035b682cddc2999e604609a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c"]}],"references":["https://git.kernel.org/stable/c/c61431f3b8c9824e9848a0308054f92b27fa7794","https://git.kernel.org/stable/c/f8d2690f3c5dfad1fc306f6d5d84a1d3176c3af9","https://git.kernel.org/stable/c/c03fb9c4be3b2dd0996d91e54f65407f7f475238","https://git.kernel.org/stable/c/41a2f69f091b0765f17890d8ac04852c12f25cf6","https://git.kernel.org/stable/c/18edcb9945118beb7a1b64a31a7370ecab485a79","https://git.kernel.org/stable/c/bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","https://git.kernel.org/stable/c/078deff25f8a849ecd1c3fe17b1e473b1cf44f28","https://git.kernel.org/stable/c/f88bb3606e4bd11ee035b682cddc2999e604609a"],"weaknesses":[],"ingestedAt":"2026-10-30T13:02:04.640Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99201.json","commit":"cb14bf1b43b0c9f05f7f40eae2246263fd430780","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99201","state":"PUBLISHED","datePublished":"2026-10-28T10:35:56.069Z","dateUpdated":"2026-10-30T12:42:51.128Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.400Z"},"containers":{"cna":{"title":"netlink: avoid hashing the network namespace pointer","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"c61431f3b8c9824e9848a0308054f92b27fa7794","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"f8d2690f3c5dfad1fc306f6d5d84a1d3176c3af9","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"c03fb9c4be3b2dd0996d91e54f65407f7f475238","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"41a2f69f091b0765f17890d8ac04852c12f25cf6","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"18edcb9945118beb7a1b64a31a7370ecab485a79","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"bdd55b8a8acbf6b4840ab420eb6a63774bf4593b","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"078deff25f8a849ecd1c3fe17b1e473b1cf44f28","versionType":"git"},{"version":"c428ecd1a21f1457ca3beb4df71b8a079c410e41","status":"affected","lessThan":"f88bb3606e4bd11ee035b682cddc2999e604609a","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.1","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.1","versionType":"semver"},{"version":"5.10.273","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.224","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.161","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.115","status":"unaffected","lessThanOrEqual":"6.12.*","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/netlink/af_netlink.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c61431f3b8c9824e9848a0308054f92b27fa7794"},{"url":"https://git.kernel.org/stable/c/f8d2690f3c5dfad1fc306f6d5d84a1d3176c3af9"},{"url":"https://git.kernel.org/stable/c/c03fb9c4be3b2dd0996d91e54f65407f7f475238"},{"url":"https://git.kernel.org/stable/c/41a2f69f091b0765f17890d8ac04852c12f25cf6"},{"url":"https://git.kernel.org/stable/c/18edcb9945118beb7a1b64a31a7370ecab485a79"},{"url":"https://git.kernel.org/stable/c/bdd55b8a8acbf6b4840ab420eb6a63774bf4593b"},{"url":"https://git.kernel.org/stable/c/078deff25f8a849ecd1c3fe17b1e473b1cf44f28"},{"url":"https://git.kernel.org/stable/c/f88bb3606e4bd11ee035b682cddc2999e604609a"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:42:51.128Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.10.273"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"5.15.224"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.6.161"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.12.115"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"6.18.59"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.1","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}