{"api_version":"1","generated_at":"2026-09-16T11:55:23+00:00","cve":"CVE-2026-89788","urls":{"html":"https://cve.report/CVE-2026-89788","api":"https://cve.report/api/cve/CVE-2026-89788.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89788","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89788"},"summary":{"title":"ksmbd: fix tree connection use-after-free in smb2_tree_connect()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix tree connection use-after-free in smb2_tree_connect()\n\nksmbd_tree_conn_connect() publishes a new tree connection in\nsess->tree_conns with a single reference and returns its pointer to\nsmb2_tree_connect(). The handler continues to initialize the object and\nbuild the response after publication. A concurrent session logoff can\nerase the connection and drop that reference, freeing the object while\nthe handler still uses it.\n\nBUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90\n  smb2_tree_connect (fs/smb/server/smb2pdu.c:2872)\n  handle_ksmbd_work\n  process_one_work\n  worker_thread\n  kthread\n\nAfter xa_store() succeeds, take a second reference before releasing\ntree_conns_lock. The original reference belongs to the xarray entry and\nthe second belongs to the creating smb2_tree_connect() handler.\n\nKeep the references balanced in every path:\n\n- On normal exit or an error after publication, smb2_tree_connect()\n  drops its creator reference. Error cleanup also calls\n  ksmbd_tree_conn_disconnect(), which drops the xarray reference only if\n  it removes the exact entry.\n- SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop\n  its xarray reference. The request's existing lookup reference remains\n  owned by the request and is released by the existing cleanup.\n- Session LOGOFF removes each entry and drops its xarray reference. If\n  it wins the race, later cleanup sees that the entry is gone and does\n  not drop that reference again.\n\nTo enforce this ownership, claim the disconnected state and erase the\nexact entry atomically under tree_conns_lock. This guarantees one drop\nfor the xarray reference and one drop by each in-flight user, regardless\nof which teardown path wins. If logoff removes the entry before\ninitialization completes, fail the connect instead of marking the\ndetached object TREE_CONNECTED.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 09:17:09","updated_at":"2026-09-16 09:17:09"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/4e30fbd26e84efa2e5cbec4eb11e126ac0c79313","name":"https://git.kernel.org/stable/c/4e30fbd26e84efa2e5cbec4eb11e126ac0c79313","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b5ec6c462aab1062cf5d1e667ba7c6442f737055","name":"https://git.kernel.org/stable/c/b5ec6c462aab1062cf5d1e667ba7c6442f737055","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89788","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89788","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e 4e30fbd26e84efa2e5cbec4eb11e126ac0c79313 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 33b235a6e6ebe0f05f3586a71e8d281d00f71e2e b5ec6c462aab1062cf5d1e667ba7c6442f737055 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected dd45db4d9bbc8f122a9b4db5ce94ae29fcf03d3c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7b58ee8d0b91359554cf219cd4f33872ea2afd66 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.15.145 5.16 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.71 6.2 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/server/mgmt/tree_connect.c","fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"4e30fbd26e84efa2e5cbec4eb11e126ac0c79313","status":"affected","version":"33b235a6e6ebe0f05f3586a71e8d281d00f71e2e","versionType":"git"},{"lessThan":"b5ec6c462aab1062cf5d1e667ba7c6442f737055","status":"affected","version":"33b235a6e6ebe0f05f3586a71e8d281d00f71e2e","versionType":"git"},{"status":"affected","version":"dd45db4d9bbc8f122a9b4db5ce94ae29fcf03d3c","versionType":"git"},{"status":"affected","version":"7b58ee8d0b91359554cf219cd4f33872ea2afd66","versionType":"git"},{"lessThan":"5.16","status":"affected","version":"5.15.145","versionType":"semver"},{"lessThan":"6.2","status":"affected","version":"6.1.71","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/server/mgmt/tree_connect.c","fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"6.6"},{"lessThan":"6.6","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc2","versionStartIncluding":"6.6","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15.145","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.71","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix tree connection use-after-free in smb2_tree_connect()\n\nksmbd_tree_conn_connect() publishes a new tree connection in\nsess->tree_conns with a single reference and returns its pointer to\nsmb2_tree_connect(). The handler continues to initialize the object and\nbuild the response after publication. A concurrent session logoff can\nerase the connection and drop that reference, freeing the object while\nthe handler still uses it.\n\nBUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90\n  smb2_tree_connect (fs/smb/server/smb2pdu.c:2872)\n  handle_ksmbd_work\n  process_one_work\n  worker_thread\n  kthread\n\nAfter xa_store() succeeds, take a second reference before releasing\ntree_conns_lock. The original reference belongs to the xarray entry and\nthe second belongs to the creating smb2_tree_connect() handler.\n\nKeep the references balanced in every path:\n\n- On normal exit or an error after publication, smb2_tree_connect()\n  drops its creator reference. Error cleanup also calls\n  ksmbd_tree_conn_disconnect(), which drops the xarray reference only if\n  it removes the exact entry.\n- SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop\n  its xarray reference. The request's existing lookup reference remains\n  owned by the request and is released by the existing cleanup.\n- Session LOGOFF removes each entry and drops its xarray reference. If\n  it wins the race, later cleanup sees that the entry is gone and does\n  not drop that reference again.\n\nTo enforce this ownership, claim the disconnected state and erase the\nexact entry atomically under tree_conns_lock. This guarantees one drop\nfor the xarray reference and one drop by each in-flight user, regardless\nof which teardown path wins. If logoff removes the entry before\ninitialization completes, fail the connect instead of marking the\ndetached object TREE_CONNECTED."}],"providerMetadata":{"dateUpdated":"2026-09-16T08:48:25.049Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/4e30fbd26e84efa2e5cbec4eb11e126ac0c79313"},{"url":"https://git.kernel.org/stable/c/b5ec6c462aab1062cf5d1e667ba7c6442f737055"}],"title":"ksmbd: fix tree connection use-after-free in smb2_tree_connect()","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89788","datePublished":"2026-09-16T08:48:25.049Z","dateReserved":"2026-09-11T19:38:34.766Z","dateUpdated":"2026-09-16T08:48:25.049Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 09:17:09","lastModifiedDate":"2026-09-16 09:17:09","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89788","Ordinal":"1","Title":"ksmbd: fix tree connection use-after-free in smb2_tree_connect()","CVE":"CVE-2026-89788","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89788","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix tree connection use-after-free in smb2_tree_connect()\n\nksmbd_tree_conn_connect() publishes a new tree connection in\nsess->tree_conns with a single reference and returns its pointer to\nsmb2_tree_connect(). The handler continues to initialize the object and\nbuild the response after publication. A concurrent session logoff can\nerase the connection and drop that reference, freeing the object while\nthe handler still uses it.\n\nBUG: KASAN: slab-use-after-free in smb2_tree_connect+0xe3d/0xf90\n  smb2_tree_connect (fs/smb/server/smb2pdu.c:2872)\n  handle_ksmbd_work\n  process_one_work\n  worker_thread\n  kthread\n\nAfter xa_store() succeeds, take a second reference before releasing\ntree_conns_lock. The original reference belongs to the xarray entry and\nthe second belongs to the creating smb2_tree_connect() handler.\n\nKeep the references balanced in every path:\n\n- On normal exit or an error after publication, smb2_tree_connect()\n  drops its creator reference. Error cleanup also calls\n  ksmbd_tree_conn_disconnect(), which drops the xarray reference only if\n  it removes the exact entry.\n- SMB2 TREE_DISCONNECT uses the same helper to remove the entry and drop\n  its xarray reference. The request's existing lookup reference remains\n  owned by the request and is released by the existing cleanup.\n- Session LOGOFF removes each entry and drops its xarray reference. If\n  it wins the race, later cleanup sees that the entry is gone and does\n  not drop that reference again.\n\nTo enforce this ownership, claim the disconnected state and erase the\nexact entry atomically under tree_conns_lock. This guarantees one drop\nfor the xarray reference and one drop by each in-flight user, regardless\nof which teardown path wins. If logoff removes the entry before\ninitialization completes, fail the connect instead of marking the\ndetached object TREE_CONNECTED.","Type":"Description","Title":"ksmbd: fix tree connection use-after-free in smb2_tree_connect()"}]}}}