{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-74556", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-15T05:44:03.916Z", "datePublished": "2026-08-15T12:28:01.359Z", "dateUpdated": "2026-08-19T16:38:57.393Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:38:57.393Z" }, "descriptions": [ { "lang": "en", "value": "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-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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - A malicious or compromised iSCSI target delivers crafted SCSI Command Response PDUs over the established TCP iSCSI session; reception flows through iscsi_sw_tcp_recv/iscsi_tcp_recv_skb into iscsi_tcp_hdr_dissect without local access.\nAC:L - The attacker controls the target and can set DataSegmentLength between 8193 and negotiated max_recv_dlength (open-iscsi commonly 262144) on SCSI_CMD_RSP for any outstanding command ITT; no races or victim-specific heap layout are required.\nPR:N - No privileges on the victim host are needed; a remote attacker acting as or MITMing the iSCSI target sends malicious responses after session login, independent of victim user accounts or capabilities.\nUI:N - On systems with persistent iSCSI sessions (cloud VMs, SAN-boot hosts, Kubernetes iSCSI volumes), exploitation triggers automatically during normal SCSI I/O when command responses are received; no victim action is needed at attack time.\nS:U - Heap corruption is confined to the kernel iSCSI initiator on the affected host; successful exploitation yields kernel compromise or DoS within the same security authority, not a VM escape or cross-boundary scope change.\nC:H - iscsi_tcp_segment_recv memcpy writes up to max_recv_dlength bytes into an 8192-byte conn->data buffer, causing a large heap overflow whose controlled corruption can be leveraged for arbitrary kernel memory disclosure.\nI:H - Attacker-controlled response data is copied past the fixed conn->data allocation via iscsi_tcp_data_recv_prep/iscsi_segment_init_linear, enabling heap metadata/object corruption exploitable for arbitrary kernel write and privilege escalation.\nA:H - Overflowing the conn->data heap buffer can immediately corrupt adjacent kernel allocations and cause oops/panic; a malicious target can repeatedly trigger this on active sessions to deny storage availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/scsi/libiscsi_tcp.c" ], "versions": [ { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "a51812842084fd390590ab8dc0431f10c73ddc56", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "a8f94cc9f0e5759252551be3a172960c57f21f54", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "f1a3a51fc5dba0e99532379665069f1700da6b44", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "c97b5265cc47775f77fd2a23d6bde0426997b233", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "084af0253673425ce2ae62e3c7f74f0dd023711b", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "72815741715bd41556dac5eeb068bf0f8af06ee7", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676", "status": "affected", "versionType": "git" }, { "version": "a081c13e39b5c17052a7b46fafa61019c4c110ff", "lessThan": "c1dea15f819cded9b3faf58f8bec72323568b6e6", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/scsi/libiscsi_tcp.c" ], "versions": [ { "version": "2.6.29", "status": "affected" }, { "version": "0", "lessThan": "2.6.29", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.265", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.216", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.151", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.103", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.44", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.8", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "2.6.29", "versionEndExcluding": "5.10.265" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "5.15.216" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.6.151" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.12.103" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "6.18.44" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "7.1.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.29", "versionEndExcluding": "7.2" } ] } ] } ], "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" } ], "title": "scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer", "x_generator": { "engine": "bippy-1.2.0" } } } }