CVE-2026-99277

{"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can keep the session and its channel list alive after\nthose removals.\n\nConnection cleanup can no longer find the unpublished session to remove its\nchannels.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"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/smb/server/mgmt/user_session.c", "fs/smb/server/smb2pdu.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "4b333aed69cfc2c8687b86b6a4364a0dffc16dd8", "status": "affected", "version": "d7fd1f98607f2cd358e583f9548bdf0173090a86", "versionType": "git"}, {"lessThan": "add8d7fb04efe564193df73581889c62fc0016f1", "status": "affected", "version": "d7fd1f98607f2cd358e583f9548bdf0173090a86", "versionType": "git"}, {"status": "affected", "version": "c99ea7855124ca1428a1e59c2b4590aaef34eacf", "versionType": "git"}, {"lessThan": "7.3", "status": "affected", "version": "7.2.8", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/smb/server/mgmt/user_session.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": "7.3"}, {"lessThan": "7.3", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.3.*", "status": "unaffected", "version": "7.3.2", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.4-rc1", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-99277", "lastModified": "2026-11-10T17:17:57.803", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 7.5, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.6, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-11-07T14:17:03.080", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4b333aed69cfc2c8687b86b6a4364a0dffc16dd8"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/add8d7fb04efe564193df73581889c62fc0016f1"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: kernel: ksmbd: Denial of Service via use-after-free in session channel handling", "id": "2568638", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2568638"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-825", "details": ["A flaw was found in the Linux kernel's ksmbd, an in-kernel Server Message Block (SMB) server. A remote attacker could exploit this flaw to cause a denial of service (DoS) or potentially corrupt kernel memory. The issue occurs due to improper reference counting during session channel management, where a connection structure can be freed while still in use by an active session channel. By triggering concurrent SMB operations, an attacker can induce a use-after-free condition leading to a system crash."], "mitigation": {"lang": "en:us", "value": "Disable the ksmbd kernel module to prevent it from loading:\n1. Create a configuration file in /etc/modprobe.d to disable module loading:\n```\necho \"install ksmbd /bin/true\" > /etc/modprobe.d/ksmbd.conf\n```\n2. If the module is currently loaded, unload it:\n```\nmodprobe -r ksmbd\n```\nCaveats:\nDisabling the ksmbd module prevents the system from running the in-kernel SMB server. If the module is actively in use by SMB sessions, dependent services must be stopped prior to unloading, or a system restart may be required to apply the changes."}, "name": "CVE-2026-99277", "package_state": [{"cpe": "cpe:/a:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:rhel_els:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:rhel_els:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:rhel_els:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/a:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/a:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/a:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:5", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-10", "product_name": "Red Hat OpenShift Container Platform 5"}, {"cpe": "cpe:/a:redhat:openshift:5", "fix_state": "Not affected", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 5"}], "public_date": "2026-11-07T14:08:46Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-99277\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-99277\nhttps://git.kernel.org/stable/c/4b333aed69cfc2c8687b86b6a4364a0dffc16dd8\nhttps://git.kernel.org/stable/c/add8d7fb04efe564193df73581889c62fc0016f1"], "statement": "This vulnerability is rated as Moderate because successful exploitation requires authenticated network access to establish SMB session channels and primarily leads to a denial of service via a kernel crash. In Red Hat Enterprise Linux, the in-kernel SMB server (ksmbd) is not loaded or configured by default, as standard installations rely on user-space Samba for SMB file sharing. Only systems where administrators have explicitly enabled and deployed ksmbd are exposed to this flaw.", "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d7fd1f98607f2cd358e583f9548bdf0173090a86,4b333aed69cfc2c8687b86b6a4364a0dffc16dd8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d7fd1f98607f2cd358e583f9548bdf0173090a86,add8d7fb04efe564193df73581889c62fc0016f1)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[c99ea7855124ca1428a1e59c2b4590aaef34eacf,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.2.8,7.3)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.3,*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,7.3)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.3.2,7.4.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.4-rc1,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d7fd1f98607f2cd358e583f9548bdf0173090a86,4b333aed69cfc2c8687b86b6a4364a0dffc16dd8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d7fd1f98607f2cd358e583f9548bdf0173090a86,add8d7fb04efe564193df73581889c62fc0016f1)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[c99ea7855124ca1428a1e59c2b4590aaef34eacf,*]"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.2.8,7.3)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.3,*]"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[0,7.3)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.3.2,7.4.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "semver", "value": "[7.4-rc1,*]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-11-07T15:30:07.507518+00:00", "updated": "2026-11-08T04:30:14.846511+00:00", "vendors": ["linux", "linux$PRODUCT$linux", "linux$PRODUCT$linux_kernel"]}