{"id":"CVE-2026-53175","title":"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 th…","summary":"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 th…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 6.18.3, < 6.18.36","linux_kernel >= 6.19.1, < 7.0.13","linux_kernel = 6.12.93","linux_kernel = 6.19","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.13"],"published":"2026-06-25","updated":"2026-07-06","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-53175","references":[{"url":"https://git.kernel.org/stable/c/010c3313a4d178dc2d3ce958d2e5cb055e2864c1","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/0e823ca0e7391630784ae7dd0981b7ad170a93d9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/32594b09854970d7ba83eb2dc8c69a2edd158c8e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/89b909e9704587bfecc1aab1d37e98faee03b9f9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c22599cc90e1cd5f8129c8670bd68a02ff7177b4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://access.redhat.com/security/cve/CVE-2026-53175","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2492840","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53175.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}],"tags":["nvd"],"epss":0.00313,"epssPercentile":0.2445,"ingestedAt":"2026-07-06T17:44:51.375Z","slug":"CVE-2026-53175","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `linux_kernel >= 6.18.3, < 6.18.36`\n- `linux_kernel >= 6.19.1, < 7.0.13`\n- `linux_kernel = 6.12.93`\n- `linux_kernel = 6.19`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.13`","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}