{ "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": "2026-10-30T12:41:38.581Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-30T12:41:38.581Z" }, "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": "676392184785ace61e939831e7ca44a03d438c3b", "lessThan": "a07dfb33112a42437f9d2d0bfd35c68575257381", "status": "affected", "versionType": "git" }, { "version": "ef572ffa8eb44111eed2925fbb2adca78bdcbf61", "lessThan": "1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff", "status": "affected", "versionType": "git" }, { "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": "2ba03cecb12ac7ac9e0170e251543c56832d9959", "status": "affected", "versionType": "git" }, { "version": "5.15.145", "lessThan": "5.15.224", "status": "affected", "versionType": "semver" }, { "version": "6.1.40", "lessThan": "6.1.191", "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": "5.15.224", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.191", "lessThanOrEqual": "6.1.*", "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": "5.15.145", "versionEndExcluding": "5.15.224" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.40", "versionEndExcluding": "6.1.191" }, { "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": "6.4.5" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a07dfb33112a42437f9d2d0bfd35c68575257381" }, { "url": "https://git.kernel.org/stable/c/1f73a6d40f4d1bae4f3491c0ec1ea8ee6ce035ff" }, { "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" } } } }