{"id":"CVE-2026-53175","summary":"inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ninet: frags: fix use-after-free caused by the fqdir_pre_exit() flush\n\nOn netns teardown, fqdir_pre_exit() walks the fqdir rhashtable and\nflushes every fragment queue that is not yet complete using\ninet_frag_queue_flush(). That helper frees all the skbs queued on the\nfragment queue but does not set INET_FRAG_COMPLETE, and leaves\nq-\u003efragments_tail and q-\u003elast_run_head pointing at the freed skbs.\nThe queue itself stays in the rhashtable.\n\nfqdir_pre_exit() first lowers high_thresh to 0 to stop new queue lookups,\nbut it cannot stop a fragment that already obtained the queue through\ninet_frag_find() earlier and stalled just before taking the queue lock.\nOnce that fragment resumes after the flush and takes the queue lock,\nit passes the INET_FRAG_COMPLETE check and then dereferences the freed\nfragments_tail. inet_frag_queue_insert() reads FRAG_CB() and -\u003elen of\nthat pointer and, on the append path, writes -\u003enext_frag, causing a\nslab use-after-free. IPv6, nf_conntrack_reasm6 and 6lowpan reassembly\nshare the same flush path and are affected as well.\n\nReset rb_fragments, fragments_tail and last_run_head in\ninet_frag_queue_flush() so a flushed queue no longer points at the\nfreed skbs. A fragment that resumes after the flush and takes the\nqueue lock then finds an empty queue and starts a new run instead of\ndereferencing the freed fragments_tail. ip_frag_reinit() already\nperformed this reset after its own flush, so drop the now duplicate\ncode there.","modified":"2026-07-08T08:13:44.006393584Z","published":"2026-06-25T08:38:52.034Z","related":["CGA-pch9-m3fw-5p36"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53175.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/010c3313a4d178dc2d3ce958d2e5cb055e2864c1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0e823ca0e7391630784ae7dd0981b7ad170a93d9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/32594b09854970d7ba83eb2dc8c69a2edd158c8e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/89b909e9704587bfecc1aab1d37e98faee03b9f9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c22599cc90e1cd5f8129c8670bd68a02ff7177b4"},{"type":"WEB","url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53175.json"},{"type":"ADVISORY","url":"https://access.redhat.com/security/cve/CVE-2026-53175"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53175.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-53175"},{"type":"REPORT","url":"https://bugzilla.redhat.com/show_bug.cgi?id=2492840"},{"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":"22ee4010866da81aeee08e1ea3fddbe418feb212"},{"fixed":"0e823ca0e7391630784ae7dd0981b7ad170a93d9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"543555954b1ee8d1903a7020324efb41b0c97428"},{"fixed":"c22599cc90e1cd5f8129c8670bd68a02ff7177b4"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c70df25214ac9b32b53e18e6ae3b8f073ffa6903"},{"fixed":"89b909e9704587bfecc1aab1d37e98faee03b9f9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"006a5035b495dec008805df249f92c22c89c3d2e"},{"fixed":"010c3313a4d178dc2d3ce958d2e5cb055e2864c1"},{"fixed":"32594b09854970d7ba83eb2dc8c69a2edd158c8e"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.93"},{"fixed":"6.12.94"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.18.3"},{"fixed":"6.18.36"}]}],"versions":["v6.12.93","v6.18.35","v6.18.34","v6.18.33","v6.18.32","v6.18.31","v6.18.30","v6.18.29","v6.18.28","v6.18.27","v6.18.26","v6.18.25","v6.18.24","v6.18.23","v6.18.22","v6.18.21","v6.18.20","v6.18.19","v6.18.18","v6.18.17","v6.18.16","v6.18.15","v6.18.14","v6.18.13","v6.18.12","v6.18.11","v6.18.10","v6.18.9","v6.18.8","v6.18.7","v6.18.6","v6.18.5","v6.18.4","v6.18.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53175.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.94"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.36"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.13"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-53175.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}