{"id":"AZL-83726","summary":"CVE-2026-31665 affecting package kernel for versions less than 6.6.137.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: fix use-after-free in timeout object destroy\n\nnft_ct_timeout_obj_destroy() frees the timeout object with kfree()\nimmediately after nf_ct_untimeout(), without waiting for an RCU grace\nperiod. Concurrent packet processing on other CPUs may still hold\nRCU-protected references to the timeout object obtained via\nrcu_dereference() in nf_ct_timeout_data().\n\nAdd an rcu_head to struct nf_ct_timeout and use kfree_rcu() to defer\nfreeing until after an RCU grace period, matching the approach already\nused in nfnetlink_cttimeout.c.\n\nKASAN report:\n BUG: KASAN: slab-use-after-free in nf_conntrack_tcp_packet+0x1381/0x29d0\n Read of size 4 at addr ffff8881035fe19c by task exploit/80\n\n Call Trace:\n  nf_conntrack_tcp_packet+0x1381/0x29d0\n  nf_conntrack_in+0x612/0x8b0\n  nf_hook_slow+0x70/0x100\n  __ip_local_out+0x1b2/0x210\n  tcp_sendmsg_locked+0x722/0x1580\n  __sys_sendto+0x2d8/0x320\n\n Allocated by task 75:\n  nft_ct_timeout_obj_init+0xf6/0x290\n  nft_obj_init+0x107/0x1b0\n  nf_tables_newobj+0x680/0x9c0\n  nfnetlink_rcv_batch+0xc29/0xe00\n\n Freed by task 26:\n  nft_obj_destroy+0x3f/0xa0\n  nf_tables_trans_destroy_work+0x51c/0x5c0\n  process_one_work+0x2c4/0x5a0","modified":"2026-08-28T17:47:34.359024964Z","published":"2026-04-24T15:16:46Z","upstream":["CVE-2026-31665"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31665"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.137.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-83726.json"}}],"schema_version":"1.9.0"}