{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-99083", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.390Z", "datePublished": "2026-10-23T12:45:01.735Z", "dateUpdated": "2026-10-26T06:56:58.783Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-26T06:56:58.783Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work->next_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH"}, "scenarios": [{"lang": "en", "value": "AV:N - ksmbd_conn_handler_loop() receives the compound request over TCP/445, and __process_request() dispatches its non-first SMB2 SESSION_SETUP to smb2_sess_setup() and krb5_authenticate(). The SESSION_SETUP SecurityBuffer carries the Kerberos AP-REQ that produces the AP-REP copied by the patched path.\nAC:L - The same authenticated peer can create directory entries, request a sized QUERY_DIRECTORY response, and place SESSION_SETUP later in the compound, controlling next_smb2_rsp_hdr_off before supplying its valid AP-REQ; no race or external actor is required.\nPR:L - ksmbd_krb5_authenticate() checks KSMBD_USER_FLAG_OK before its length check and memcpy; ksmbd.mountd sets it only after krb5_rd_req() accepts the AP-REQ and usm_handle_login_request() recognizes the account. An ordinary valid Kerberos account suffices, but an unauthenticated peer cannot reach the write.\nUI:N - The peer opens the session, prepares the prior compound response, and sends the Kerberos SESSION_SETUP itself; no victim user must open, mount, or approve anything.\nS:U - ksmbd_krb5_authenticate() corrupts memory adjacent to the host kernel's response_buf allocation; this remains within the same kernel security authority and crosses no VM, IOMMU, or sandbox boundary.\nC:H - The AP-REP memcpy in ksmbd_krb5_authenticate() can overrun response_buf and corrupt adjacent heap objects; exploitable kernel heap corruption can be converted into a memory-read primitive exposing arbitrary kernel data.\nI:H - The memcpy writes resp->spnego_blob_len AP-REP bytes beyond response_buf into adjacent kernel heap memory, enabling corruption of object metadata or control data and potential kernel code execution.\nA:H - Writing the AP-REP beyond response_buf can corrupt adjacent allocations or allocator metadata and trigger KASAN, an oops, or a kernel panic; the authenticated SMB peer can repeat the compound request."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["fs/smb/server/smb2pdu.c"], "versions": [{"version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "lessThan": "59c6dcc5dd9dafe764ca0d40525933b2be69b059", "status": "affected", "versionType": "git"}, {"version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "lessThan": "80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a", "status": "affected", "versionType": "git"}, {"version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "lessThan": "517404e157395d0f8da125ca956c566895dfcd06", "status": "affected", "versionType": "git"}, {"version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "lessThan": "4722d06b2907585074252061b1024a696c1cfc23", "status": "affected", "versionType": "git"}, {"version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "lessThan": "23a0be6a84a38ac169eeab49017934e8e27c65f0", "status": "affected", "versionType": "git"}, {"version": "676392184785ace61e939831e7ca44a03d438c3b", "status": "affected", "versionType": "git"}, {"version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61", "status": "affected", "versionType": "git"}, {"version": "2ba03cecb12ac7ac9e0170e251543c56832d9959", "status": "affected", "versionType": "git"}, {"version": "5.15.145", "lessThan": "5.16", "status": "affected", "versionType": "semver"}, {"version": "6.1.40", "lessThan": "6.2", "status": "affected", "versionType": "semver"}, {"version": "6.4.5", "lessThan": "6.5", "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/smb2pdu.c"], "versions": [{"version": "6.5", "status": "affected"}, {"version": "0", "lessThan": "6.5", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.114", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.58", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.12", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "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": "6.5", "versionEndExcluding": "6.6.160"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "6.12.114"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "6.18.58"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "7.2.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5", "versionEndExcluding": "7.3"}, {"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": "6.1.40"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4.5"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"}, {"url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"}, {"url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"}, {"url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"}, {"url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"}], "title": "ksmbd: fix heap out-of-bounds write in krb5_authenticate()", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["fs/smb/server/smb2pdu.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "59c6dcc5dd9dafe764ca0d40525933b2be69b059", "status": "affected", "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "versionType": "git"}, {"lessThan": "80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a", "status": "affected", "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "versionType": "git"}, {"lessThan": "517404e157395d0f8da125ca956c566895dfcd06", "status": "affected", "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "versionType": "git"}, {"lessThan": "4722d06b2907585074252061b1024a696c1cfc23", "status": "affected", "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "versionType": "git"}, {"lessThan": "23a0be6a84a38ac169eeab49017934e8e27c65f0", "status": "affected", "version": "98422bdd4cb3ca4d08844046f6507d7ec2c2b8d8", "versionType": "git"}, {"status": "affected", "version": "676392184785ace61e939831e7ca44a03d438c3b", "versionType": "git"}, {"status": "affected", "version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61", "versionType": "git"}, {"status": "affected", "version": "2ba03cecb12ac7ac9e0170e251543c56832d9959", "versionType": "git"}, {"lessThan": "5.16", "status": "affected", "version": "5.15.145", "versionType": "semver"}, {"lessThan": "6.2", "status": "affected", "version": "6.1.40", "versionType": "semver"}, {"lessThan": "6.5", "status": "affected", "version": "6.4.5", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["fs/smb/server/smb2pdu.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "6.5"}, {"lessThan": "6.5", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "6.6.*", "status": "unaffected", "version": "6.6.160", "versionType": "semver"}, {"lessThanOrEqual": "6.12.*", "status": "unaffected", "version": "6.12.114", "versionType": "semver"}, {"lessThanOrEqual": "6.18.*", "status": "unaffected", "version": "6.18.58", "versionType": "semver"}, {"lessThanOrEqual": "7.2.*", "status": "unaffected", "version": "7.2.12", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.3", "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: fix heap out-of-bounds write in krb5_authenticate()\n\nIn krb5_authenticate(), out_len is calculated to determine available\nheadroom in response_buf for the incoming Kerberos AP-REP token. However,\nwhen SMB2_SESSION_SETUP is processed as a non-first element of a compounded\nSMB2 request, the calculation omits work->next_smb2_rsp_hdr_off.\n\nThis causes out_len to overstate remaining buffer headroom by\nthe cumulative size of prior responses in the compound chain. Consequently,\nthe length check in ksmbd_krb5_authenticate()\n(*out_len <= resp->spnego_blob_len) passes erroneously, allowing memcpy()\nto write the AP-REP blob past the end of response_buf into adjacent kernel\nheap memory.\n\nFix this by subtracting work->next_smb2_rsp_hdr_off when computing out_len,\nensuring it accurately reflects physical remaining buffer space."}], "id": "CVE-2026-99083", "lastModified": "2026-10-26T07:17:18.627", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-10-23T13:17:32.577", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/23a0be6a84a38ac169eeab49017934e8e27c65f0"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4722d06b2907585074252061b1024a696c1cfc23"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/517404e157395d0f8da125ca956c566895dfcd06"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/59c6dcc5dd9dafe764ca0d40525933b2be69b059"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/80af1bde97d5a85ad6f2c40ca894ccc8fa75a27a"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: ksmbd: fix heap out-of-bounds write in krb5_authenticate()", "id": "2559773", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2559773"}, "csaw": false, "cvss3": {"cvss3_base_score": "9.8", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-787", "details": ["A flaw was found in the Linux kernel's ksmbd Server Message Block (SMB) server. When handling compounded SMB requests during Kerberos authentication, the server incorrectly calculates available buffer space, leading to a heap-based out-of-bounds write. A remote attacker could exploit this vulnerability by sending specially crafted requests, potentially allowing arbitrary code execution or causing a system crash that results in a Denial of Service (DoS)."], "name": "CVE-2026-99083", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o: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"}], "public_date": "2026-10-23T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-99083\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-99083\nhttps://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-99083.mbox"], "threat_severity": "Critical"}