{"api_version":"1","generated_at":"2026-09-13T04:36:18+00:00","cve":"CVE-2026-89655","urls":{"html":"https://cve.report/CVE-2026-89655","api":"https://cve.report/api/cve/CVE-2026-89655.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89655","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89655"},"summary":{"title":"ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock\n\nlist_for_each_entry() iterates ci->i_cap_flush_list but drops\ni_ceph_lock to send cap messages.  During the unlock window,\nhandle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries\nwith tid <= flush_tid from the list, release i_ceph_lock, and free\nthem via ceph_free_cap_flush() outside any lock.  When the original\nthread reacquires i_ceph_lock and the for-loop macro advances via\ncf = list_next_entry(cf, i_list), it dereferences cf->i_list.next\non freed memory.\n\nThe race timeline:\n\n  __kick_flushing_caps()              handle_cap_flush_ack()\n  -----------------------             -----------------------\n  holds i_ceph_lock        <---\n  iterates to cf (tid=10)\n  prepares FLUSH message\n  drops i_ceph_lock        <---\n  __send_cap() ── FLUSH(tid=10)\n\t                              MDS sends FLUSH_ACK(tid=10)\n                           --->       acquires i_ceph_lock\n                                      cf->tid(10) <= flush_tid(10),\n                                      detaches cf from i_cap_flush_list\n                                      drops i_ceph_lock\n                                      ceph_free_cap_flush(cf) <- frees it!\n  acquires i_ceph_lock     <---\n  for-loop advances:\n    cf = list_next_entry(cf, i_list)\n      -- UAF on freed cf->i_list.next\n\nThe cf was just sent by __kick_flushing_caps itself via __send_cap().\nThe MDS may respond with FLUSH_ACK quickly enough that\nhandle_cap_flush_ack() frees cf before __kick_flushing_caps can\nfinish the iteration.\n\nFix by converting to a manual while loop: save the next pointer\nunder i_ceph_lock before dropping it, then use the saved pointer\nafter reacquiring, so the potentially-freed cf is never accessed again.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-11 20:19:51","updated_at":"2026-09-11 20:19:51"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/2701431aa3cc8b23efe6890182e7b04f5e76fab5","name":"https://git.kernel.org/stable/c/2701431aa3cc8b23efe6890182e7b04f5e76fab5","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7af4c4f01305b0935adf6d4301b1ec407025485d","name":"https://git.kernel.org/stable/c/7af4c4f01305b0935adf6d4301b1ec407025485d","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/fe46746087b5b9c5bb2d022df6c7819218494ced","name":"https://git.kernel.org/stable/c/fe46746087b5b9c5bb2d022df6c7819218494ced","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/2dba24dcd5050be4b7b119e6f0b01f62203b5d26","name":"https://git.kernel.org/stable/c/2dba24dcd5050be4b7b119e6f0b01f62203b5d26","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89655","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89655","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 2701431aa3cc8b23efe6890182e7b04f5e76fab5 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 fe46746087b5b9c5bb2d022df6c7819218494ced git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 2dba24dcd5050be4b7b119e6f0b01f62203b5d26 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 7af4c4f01305b0935adf6d4301b1ec407025485d git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.109 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.50 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.2.4 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.109 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.50 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.4 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"89655","cve":"CVE-2026-89655","epss":"0.002000000","percentile":"0.099720000","score_date":"2026-09-12","updated_at":"2026-09-13 00:08:17"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/ceph/caps.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"2701431aa3cc8b23efe6890182e7b04f5e76fab5","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"fe46746087b5b9c5bb2d022df6c7819218494ced","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"2dba24dcd5050be4b7b119e6f0b01f62203b5d26","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"7af4c4f01305b0935adf6d4301b1ec407025485d","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"6.12.109","status":"affected","version":"0","versionType":"semver"},{"lessThan":"6.18.50","status":"affected","version":"0","versionType":"semver"},{"lessThan":"7.2.4","status":"affected","version":"0","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/ceph/caps.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.109","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.50","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.109","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.50","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.4","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock\n\nlist_for_each_entry() iterates ci->i_cap_flush_list but drops\ni_ceph_lock to send cap messages.  During the unlock window,\nhandle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries\nwith tid <= flush_tid from the list, release i_ceph_lock, and free\nthem via ceph_free_cap_flush() outside any lock.  When the original\nthread reacquires i_ceph_lock and the for-loop macro advances via\ncf = list_next_entry(cf, i_list), it dereferences cf->i_list.next\non freed memory.\n\nThe race timeline:\n\n  __kick_flushing_caps()              handle_cap_flush_ack()\n  -----------------------             -----------------------\n  holds i_ceph_lock        <---\n  iterates to cf (tid=10)\n  prepares FLUSH message\n  drops i_ceph_lock        <---\n  __send_cap() ── FLUSH(tid=10)\n\t                              MDS sends FLUSH_ACK(tid=10)\n                           --->       acquires i_ceph_lock\n                                      cf->tid(10) <= flush_tid(10),\n                                      detaches cf from i_cap_flush_list\n                                      drops i_ceph_lock\n                                      ceph_free_cap_flush(cf) <- frees it!\n  acquires i_ceph_lock     <---\n  for-loop advances:\n    cf = list_next_entry(cf, i_list)\n      -- UAF on freed cf->i_list.next\n\nThe cf was just sent by __kick_flushing_caps itself via __send_cap().\nThe MDS may respond with FLUSH_ACK quickly enough that\nhandle_cap_flush_ack() frees cf before __kick_flushing_caps can\nfinish the iteration.\n\nFix by converting to a manual while loop: save the next pointer\nunder i_ceph_lock before dropping it, then use the saved pointer\nafter reacquiring, so the potentially-freed cf is never accessed again."}],"providerMetadata":{"dateUpdated":"2026-09-11T19:45:44.841Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/2701431aa3cc8b23efe6890182e7b04f5e76fab5"},{"url":"https://git.kernel.org/stable/c/fe46746087b5b9c5bb2d022df6c7819218494ced"},{"url":"https://git.kernel.org/stable/c/2dba24dcd5050be4b7b119e6f0b01f62203b5d26"},{"url":"https://git.kernel.org/stable/c/7af4c4f01305b0935adf6d4301b1ec407025485d"}],"title":"ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89655","datePublished":"2026-09-11T19:45:44.841Z","dateReserved":"2026-09-11T19:38:34.743Z","dateUpdated":"2026-09-11T19:45:44.841Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-11 20:19:51","lastModifiedDate":"2026-09-11 20:19:51","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89655","Ordinal":"1","Title":"ceph: fix UAF in __kick_flushing_caps() on cf entry freed during","CVE":"CVE-2026-89655","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89655","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock\n\nlist_for_each_entry() iterates ci->i_cap_flush_list but drops\ni_ceph_lock to send cap messages.  During the unlock window,\nhandle_cap_flush_ack() can acquire i_ceph_lock, detach cf entries\nwith tid <= flush_tid from the list, release i_ceph_lock, and free\nthem via ceph_free_cap_flush() outside any lock.  When the original\nthread reacquires i_ceph_lock and the for-loop macro advances via\ncf = list_next_entry(cf, i_list), it dereferences cf->i_list.next\non freed memory.\n\nThe race timeline:\n\n  __kick_flushing_caps()              handle_cap_flush_ack()\n  -----------------------             -----------------------\n  holds i_ceph_lock        <---\n  iterates to cf (tid=10)\n  prepares FLUSH message\n  drops i_ceph_lock        <---\n  __send_cap() ── FLUSH(tid=10)\n\t                              MDS sends FLUSH_ACK(tid=10)\n                           --->       acquires i_ceph_lock\n                                      cf->tid(10) <= flush_tid(10),\n                                      detaches cf from i_cap_flush_list\n                                      drops i_ceph_lock\n                                      ceph_free_cap_flush(cf) <- frees it!\n  acquires i_ceph_lock     <---\n  for-loop advances:\n    cf = list_next_entry(cf, i_list)\n      -- UAF on freed cf->i_list.next\n\nThe cf was just sent by __kick_flushing_caps itself via __send_cap().\nThe MDS may respond with FLUSH_ACK quickly enough that\nhandle_cap_flush_ack() frees cf before __kick_flushing_caps can\nfinish the iteration.\n\nFix by converting to a manual while loop: save the next pointer\nunder i_ceph_lock before dropping it, then use the saved pointer\nafter reacquiring, so the potentially-freed cf is never accessed again.","Type":"Description","Title":"ceph: fix UAF in __kick_flushing_caps() on cf entry freed during"}]}}}