{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99277","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-25T10:25:14.405Z","datePublished":"2026-11-07T14:08:46.710Z","dateUpdated":"2026-11-10T16:57:40.367Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-11-10T16:57:40.367Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: hold a connection reference for each session channel\n\nksmbd_session_unregister() removes a session from the global and per-\nconnection tables before dropping the table reference. A concurrent\nreference holder can keep the session and its channel list alive after\nthose removals.\n\nConnection cleanup can no longer find the unpublished session to remove its\nchannels. Since a channel only stores a raw conn pointer, the connection\ncan be freed while another session reference holder is still accessing it,\nfor example during SMB3.1.1 binding or a procfs read.\n\nTake a connection reference when registering a channel and release it on\ninsertion failure, channel removal, or final session destruction. Keep the\nchannels and signing keys until the session is destroyed so a response can\nstill be signed after the session has been unregistered."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - register_session_channel() runs from smb2_sess_setup() after ksmbd_conn_handler_loop() queues an SMB2 SESSION_SETUP read from the TCP socket. That command stores the connection in chann->conn without a reference; a later failing SESSION_SETUP calls ksmbd_session_unregister(), and ksmbd_conn_free() can free it while the channel still points at it.\nAC:H - ksmbd_session_unregister() drops an established session only after session_setup_reauth sets SMB2_SESSION_IN_PROGRESS because sess->kerberos_expiry has passed. The attacker's chann->conn->cipher_type read is smb2_sess_setup()'s SMB 3.1.1 binding arm, entered only when KSMBD_GLOBAL_FLAG_SMB3_MULTICHANNEL is already set, immediately after ksmbd_session_lookup_slowpath(), with no delay the attacker can hold across __ksmbd_conn_release_work().\nPR:L - register_session_channel() writes chann->conn only after ntlm_authenticate() or krb5_authenticate() succeeds, and the reauth path that unregisters a session which already has channels depends on kerberos_expiry set by ksmbd_krb5_authenticate(). A SESSION_SETUP rejected before authentication stores no channel.\nUI:N - The client sends the SESSION_SETUP that registers the channel, the failing reauth SESSION_SETUP that calls ksmbd_session_unregister(), and the TCP close that reaches ksmbd_server_terminate_conn() and ksmbd_conn_free().\nS:U - The freed object is a ksmbd_conn in the host kernel that serves this SMB session, so the corruption stays in that kernel security authority.\nC:H - __ksmbd_conn_release_work() kfree_sensitive()s the conn while the channel keeps the pointer. smb2_sess_setup() then reads chann->conn->cipher_type, and show_proc_session() follows chan->conn->vals and inet_addr; reclaiming the slab lets those uses disclose the replacement object.\nI:H - show_proc_session() down_read()s chan->conn->session_lock through the channel's raw pointer after the connection can already have been freed, writing the rwsem of whatever reused that slot. The use-after-free of ksmbd_conn is a heap write against that allocation.\nA:H - smb2_sess_setup()'s read of chann->conn->cipher_type and show_proc_session()'s lock of chan->conn->session_lock both use the ksmbd_conn after __ksmbd_conn_release_work() freed it, which oopses the kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c"],"versions":[{"version":"d7fd1f98607f2cd358e583f9548bdf0173090a86","lessThan":"4b333aed69cfc2c8687b86b6a4364a0dffc16dd8","status":"affected","versionType":"git"},{"version":"d7fd1f98607f2cd358e583f9548bdf0173090a86","lessThan":"add8d7fb04efe564193df73581889c62fc0016f1","status":"affected","versionType":"git"},{"version":"c99ea7855124ca1428a1e59c2b4590aaef34eacf","status":"affected","versionType":"git"},{"version":"7.2.8","lessThan":"7.3","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/mgmt/user_session.c","fs/smb/server/smb2pdu.c"],"versions":[{"version":"7.3","status":"affected"},{"version":"0","lessThan":"7.3","status":"unaffected","versionType":"semver"},{"version":"7.3.2","lessThanOrEqual":"7.3.*","status":"unaffected","versionType":"semver"},{"version":"7.4-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.3","versionEndExcluding":"7.3.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.3","versionEndExcluding":"7.4-rc1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.2.8"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/4b333aed69cfc2c8687b86b6a4364a0dffc16dd8"},{"url":"https://git.kernel.org/stable/c/add8d7fb04efe564193df73581889c62fc0016f1"}],"title":"ksmbd: hold a connection reference for each session channel","x_generator":{"engine":"bippy-1.2.0"}}}}