{"id":"CVE-2026-74556","title":"scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer\n\niscsi_tcp_hdr_dissect() receives the data segment of several PDU types\ninto the fixed-siz…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a51812842084fd390590ab8dc0431f10c73ddc56","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a8f94cc9f0e5759252551be3a172960c57f21f54","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < f1a3a51fc5dba0e99532379665069f1700da6b44","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c97b5265cc47775f77fd2a23d6bde0426997b233","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 084af0253673425ce2ae62e3c7f74f0dd023711b","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 72815741715bd41556dac5eeb068bf0f8af06ee7","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676","Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c1dea15f819cded9b3faf58f8bec72323568b6e6","Linux 2.6.29"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-16T19:00:06.190671Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:55.568Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74556","references":[{"url":"https://git.kernel.org/stable/c/a51812842084fd390590ab8dc0431f10c73ddc56"},{"url":"https://git.kernel.org/stable/c/a8f94cc9f0e5759252551be3a172960c57f21f54"},{"url":"https://git.kernel.org/stable/c/f1a3a51fc5dba0e99532379665069f1700da6b44"},{"url":"https://git.kernel.org/stable/c/c97b5265cc47775f77fd2a23d6bde0426997b233"},{"url":"https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b"},{"url":"https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7"},{"url":"https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676"},{"url":"https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6"}],"tags":["cve.org"],"epss":0.00399,"epssPercentile":0.32547,"ingestedAt":"2026-10-16T19:46:24.345Z","slug":"CVE-2026-74556","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nscsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer\n\niscsi_tcp_hdr_dissect() receives the data segment of several PDU types\ninto the fixed-size conn->data buffer, which is allocated for\nISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes.  For the LOGIN_RSP, TEXT_RSP,\nREJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU\nwhose DataSegmentLength exceeds that buffer.\n\nThe SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its\ndata segment (sense/response data) into conn->data via\niscsi_tcp_data_recv_prep(), but it does so without the same check.  The\nonly upstream bound on in.datalen is conn->max_recv_dlength, the\ninitiator's advertised MaxRecvDataSegmentLength, which is commonly\nnegotiated well above 8192 (open-iscsi defaults to 262144).  A target\nthat returns a SCSI Response with a DataSegmentLength between 8193 and\nmax_recv_dlength therefore overflows the 8192-byte conn->data buffer.\n\nOnce the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly\nlike those responses: bound the data segment, receive it into conn->data\nwhen present, and otherwise complete the PDU with no data.  Fold the\nopcode into that case group rather than duplicating the check.\n\n## Affected\n\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a51812842084fd390590ab8dc0431f10c73ddc56`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < a8f94cc9f0e5759252551be3a172960c57f21f54`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < f1a3a51fc5dba0e99532379665069f1700da6b44`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c97b5265cc47775f77fd2a23d6bde0426997b233`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 084af0253673425ce2ae62e3c7f74f0dd023711b`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < 72815741715bd41556dac5eeb068bf0f8af06ee7`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676`\n- `Linux >= a081c13e39b5c17052a7b46fafa61019c4c110ff < c1dea15f819cded9b3faf58f8bec72323568b6e6`\n- `Linux 2.6.29`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}