{"id":"CVE-2026-53175","aliases":[],"url":"https://o3.security/vulnerability/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->fragments_tail and q->last_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 ->len of\nthat pointer and, on the append path, writes ->next_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.","published":"2026-06-25T08:38:52.034Z","modified":"2026-08-26T18:28:12.488712069Z","cvss":{"score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.12.94"}],"fix":null,"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-26T18:28:12.488712069Z"}}