{"id":"CVE-2026-98099","summary":"ipv6: mcast: use rcu_assign_pointer() for __rcu list updates","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: use rcu_assign_pointer() for __rcu list updates\n\nSeveral places in net/ipv6/mcast.c update RCU-protected lists\n(np-\u003eipv6_mc_list, idev-\u003emc_list, idev-\u003emc_tomb) using direct pointer\nassignments instead of rcu_assign_pointer():\n\n1. In __ipv6_dev_mc_dec(), unlinking a group from idev-\u003emc_list did:\n       *map = ma-\u003enext;\n   without rcu_assign_pointer() while concurrent readers traverse\n   idev-\u003emc_list locklessly under rcu_read_lock().\n2. In ipv6_sock_mc_drop() and __ipv6_sock_mc_close(), unlinking a group\n   from np-\u003eipv6_mc_list directly assigned *lnk = mc_lst-\u003enext and\n   np-\u003eipv6_mc_list = mc_lst-\u003enext without rcu_assign_pointer(), racing\n   with lockless readers in inet6_mc_check().\n3. In __ipv6_sock_mc_join(), mc_lst-\u003enext was initialized to\n   np-\u003eipv6_mc_list via raw assignment before publishing mc_lst.\n4. In mld_del_delrec() and __ipv6_dev_mc_inc(), __rcu source pointers\n   passed into rcu_assign_pointer() lacked explicit dereference helpers.\n\nFix these by consistently using rcu_assign_pointer() along with\nmc_dereference() / sock_dereference().","modified":"2026-09-27T03:47:39.576161699Z","published":"2026-09-25T10:24:28.929Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98099.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0c8f56c583c3250408367880c98e4d6fbc929315"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2e46b0c9fcf7e10b64ce1630b925f47918d1f7f6"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98099.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98099"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"456b61bca8ee324ab6c18b065e632c9a8c88aa39"},{"fixed":"2e46b0c9fcf7e10b64ce1630b925f47918d1f7f6"},{"fixed":"0c8f56c583c3250408367880c98e4d6fbc929315"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98099.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.38"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98099.json"}}],"schema_version":"1.9.0"}