{"id":"CVE-2026-74715","summary":"bpf: Fix netns reference imbalance in conntrack kfuncs","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix netns reference imbalance in conntrack kfuncs\n\nThe opts argument of the BPF conntrack kfuncs can point to a shared\nmap value.  __bpf_nf_ct_lookup() and __bpf_nf_ct_alloc_entry() read\nopts-\u003enetns_id separately when acquiring and releasing the network\nnamespace reference.\n\nThe reference imbalance can occur as follows:\n\n  CPU 0                                  CPU 1\n  read opts-\u003enetns_id (-1)\n  skip get_net_ns_by_id()\n                                         write opts-\u003enetns_id (id)\n  read opts-\u003enetns_id (id)\n  put_net(net) /* no matching get */\n\nThe reverse transition leaks the reference.  Repeating the unmatched put\ncan destroy a live namespace and crash later users.\n\nThe kernel reported:\n\n  Oops: general protection fault, probably for non-canonical address\n  KASAN: null-ptr-deref in range [0x00000000000000e8-0x00000000000000ef]\n  RIP: 0010:bpf_prog_test_run_xdp+0x52c/0x1700\n  Call Trace:\n   __sys_bpf+0x1662/0x50c0\n   __x64_sys_bpf+0x73/0xb0\n   do_syscall_64+0xf9/0x540\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  Kernel panic - not syncing: Fatal exception\n\nSnapshot every input field of opts with READ_ONCE() before validating or\nusing it.  The netns_id snapshot keeps the namespace get/put pair\nbalanced, while the other snapshots keep the remaining options from\nchanging partway through an invocation.  The individual reads can still\nobserve an inconsistent combination during a concurrent update, but each\nselected field value remains stable for that invocation.","modified":"2026-08-27T11:31:06.063972286Z","published":"2026-08-22T15:33:10.262Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74715.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/e5e060eb63d10b41ab60fd955649479d99b38210"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fdeba03fea78407a8c52faa99177c9f7f29f90eb"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74715.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74715"},{"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":"aed8ee7feb44b6537af1e0b4f03365d42928be38"},{"fixed":"e5e060eb63d10b41ab60fd955649479d99b38210"},{"fixed":"fdeba03fea78407a8c52faa99177c9f7f29f90eb"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74715.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.0.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74715.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}