{"document":{"category":"csaf_vex","csaf_version":"2.0","title":"CVE-2026-53175: inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush","publisher":{"category":"vendor","name":"HarborGuard Database","namespace":"https://database.harborguard.co"},"tracking":{"id":"CVE-2026-53175","status":"final","version":"1","initial_release_date":"2026-06-25T08:38:52.034Z","current_release_date":"2026-06-28T06:39:49.567Z","revision_history":[{"date":"2026-06-25T08:38:52.034Z","number":"1","summary":"Initial machine-readable export from HarborGuard."}]},"distribution":{"tlp":{"label":"WHITE"},"text":"Public CVE data; freely redistributable."},"notes":[{"category":"description","text":"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.","title":"CVE description"}],"references":[{"category":"self","summary":"CVE-2026-53175 on HarborGuard Database","url":"https://database.harborguard.co/cve/CVE-2026-53175"},{"category":"external","summary":"CVE Record","url":"https://www.cve.org/CVERecord?id=CVE-2026-53175"},{"category":"external","summary":"git.kernel.org","url":"https://git.kernel.org/stable/c/0e823ca0e7391630784ae7dd0981b7ad170a93d9"},{"category":"external","summary":"git.kernel.org","url":"https://git.kernel.org/stable/c/c22599cc90e1cd5f8129c8670bd68a02ff7177b4"},{"category":"external","summary":"git.kernel.org","url":"https://git.kernel.org/stable/c/89b909e9704587bfecc1aab1d37e98faee03b9f9"},{"category":"external","summary":"git.kernel.org","url":"https://git.kernel.org/stable/c/010c3313a4d178dc2d3ce958d2e5cb055e2864c1"},{"category":"external","summary":"git.kernel.org","url":"https://git.kernel.org/stable/c/32594b09854970d7ba83eb2dc8c69a2edd158c8e"}]},"product_tree":{"branches":[{"category":"vendor","name":"Linux","branches":[{"category":"product_name","name":"Linux","branches":[{"category":"product_version_range","name":">=22ee4010866da81aeee08e1ea3fddbe418feb212 <0e823ca0e7391630784ae7dd0981b7ad170a93d9","product":{"name":"Linux Linux >=22ee4010866da81aeee08e1ea3fddbe418feb212 <0e823ca0e7391630784ae7dd0981b7ad170a93d9","product_id":"CSAFPID-1","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=543555954b1ee8d1903a7020324efb41b0c97428 <c22599cc90e1cd5f8129c8670bd68a02ff7177b4","product":{"name":"Linux Linux >=543555954b1ee8d1903a7020324efb41b0c97428 <c22599cc90e1cd5f8129c8670bd68a02ff7177b4","product_id":"CSAFPID-2","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=c70df25214ac9b32b53e18e6ae3b8f073ffa6903 <89b909e9704587bfecc1aab1d37e98faee03b9f9","product":{"name":"Linux Linux >=c70df25214ac9b32b53e18e6ae3b8f073ffa6903 <89b909e9704587bfecc1aab1d37e98faee03b9f9","product_id":"CSAFPID-3","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=006a5035b495dec008805df249f92c22c89c3d2e <010c3313a4d178dc2d3ce958d2e5cb055e2864c1","product":{"name":"Linux Linux >=006a5035b495dec008805df249f92c22c89c3d2e <010c3313a4d178dc2d3ce958d2e5cb055e2864c1","product_id":"CSAFPID-4","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=006a5035b495dec008805df249f92c22c89c3d2e <32594b09854970d7ba83eb2dc8c69a2edd158c8e","product":{"name":"Linux Linux >=006a5035b495dec008805df249f92c22c89c3d2e <32594b09854970d7ba83eb2dc8c69a2edd158c8e","product_id":"CSAFPID-5","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=6.12.93 <6.12.94","product":{"name":"Linux Linux >=6.12.93 <6.12.94","product_id":"CSAFPID-6","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}},{"category":"product_version_range","name":">=6.18.3 <6.18.36","product":{"name":"Linux Linux >=6.18.3 <6.18.36","product_id":"CSAFPID-7","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:*:*:*:*:*:*:*:*"}}}]}]},{"category":"vendor","name":"Linux","branches":[{"category":"product_name","name":"Linux","branches":[{"category":"product_version","name":"6.19","product":{"name":"Linux Linux 6.19","product_id":"CSAFPID-8","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"0","product":{"name":"Linux Linux 0","product_id":"CSAFPID-9","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"6.12.94","product":{"name":"Linux Linux 6.12.94","product_id":"CSAFPID-10","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"6.18.36","product":{"name":"Linux Linux 6.18.36","product_id":"CSAFPID-11","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"7.0.13","product":{"name":"Linux Linux 7.0.13","product_id":"CSAFPID-12","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}},{"category":"product_version","name":"7.1","product":{"name":"Linux Linux 7.1","product_id":"CSAFPID-13","product_identification_helper":{"cpe":"cpe:2.3:a:linux:linux:6.19:*:*:*:*:*:*:*"}}}]}]}]},"vulnerabilities":[{"cve":"CVE-2026-53175","title":"inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush","notes":[{"category":"description","text":"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.","title":"CVE description"}],"product_status":{"known_affected":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7","CSAFPID-8"],"fixed":["CSAFPID-9","CSAFPID-10","CSAFPID-11","CSAFPID-12","CSAFPID-13"]},"scores":[{"cvss_v3":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"products":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7","CSAFPID-8"]}],"remediations":[{"category":"vendor_fix","details":"Update to a fixed version: 0, 010c3313a4d178dc2d3ce958d2e5cb055e2864c1, 0e823ca0e7391630784ae7dd0981b7ad170a93d9, 32594b09854970d7ba83eb2dc8c69a2edd158c8e, 6.12.94, 6.18.36, 7.0.13, 7.1, 89b909e9704587bfecc1aab1d37e98faee03b9f9, c22599cc90e1cd5f8129c8670bd68a02ff7177b4.","product_ids":["CSAFPID-1","CSAFPID-2","CSAFPID-3","CSAFPID-4","CSAFPID-5","CSAFPID-6","CSAFPID-7","CSAFPID-8"]}]}]}