{"api_version":"1","generated_at":"2026-08-17T11:26:01+00:00","cve":"CVE-2026-74556","urls":{"html":"https://cve.report/CVE-2026-74556","api":"https://cve.report/api/cve/CVE-2026-74556.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-74556","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-74556"},"summary":{"title":"scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-15 13:18:01","updated_at":"2026-08-17 06:19:53"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"9.8","severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","data":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6","name":"https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676","name":"https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b","name":"https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7","name":"https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c97b5265cc47775f77fd2a23d6bde0426997b233","name":"https://git.kernel.org/stable/c/c97b5265cc47775f77fd2a23d6bde0426997b233","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-74556","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74556","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a081c13e39b5c17052a7b46fafa61019c4c110ff c97b5265cc47775f77fd2a23d6bde0426997b233 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a081c13e39b5c17052a7b46fafa61019c4c110ff 084af0253673425ce2ae62e3c7f74f0dd023711b git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a081c13e39b5c17052a7b46fafa61019c4c110ff 72815741715bd41556dac5eeb068bf0f8af06ee7 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a081c13e39b5c17052a7b46fafa61019c4c110ff b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected a081c13e39b5c17052a7b46fafa61019c4c110ff c1dea15f819cded9b3faf58f8bec72323568b6e6 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.29","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.29 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.151 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.103 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.44 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.8 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"74556","cve":"CVE-2026-74556","epss":"0.001570000","percentile":"0.053400000","score_date":"2026-08-16","updated_at":"2026-08-17 00:01:04"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/scsi/libiscsi_tcp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"c97b5265cc47775f77fd2a23d6bde0426997b233","status":"affected","version":"a081c13e39b5c17052a7b46fafa61019c4c110ff","versionType":"git"},{"lessThan":"084af0253673425ce2ae62e3c7f74f0dd023711b","status":"affected","version":"a081c13e39b5c17052a7b46fafa61019c4c110ff","versionType":"git"},{"lessThan":"72815741715bd41556dac5eeb068bf0f8af06ee7","status":"affected","version":"a081c13e39b5c17052a7b46fafa61019c4c110ff","versionType":"git"},{"lessThan":"b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676","status":"affected","version":"a081c13e39b5c17052a7b46fafa61019c4c110ff","versionType":"git"},{"lessThan":"c1dea15f819cded9b3faf58f8bec72323568b6e6","status":"affected","version":"a081c13e39b5c17052a7b46fafa61019c4c110ff","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/scsi/libiscsi_tcp.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.29"},{"lessThan":"2.6.29","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.151","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.103","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.44","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.8","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.151","versionStartIncluding":"2.6.29","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.103","versionStartIncluding":"2.6.29","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.44","versionStartIncluding":"2.6.29","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.8","versionStartIncluding":"2.6.29","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2","versionStartIncluding":"2.6.29","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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":{"baseScore":9.8,"baseSeverity":"CRITICAL","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"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."}]}],"providerMetadata":{"dateUpdated":"2026-08-17T05:48:38.659Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-74556","datePublished":"2026-08-15T12:28:01.359Z","dateReserved":"2026-08-15T05:44:03.916Z","dateUpdated":"2026-08-17T05:48:38.659Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-15 13:18:01","lastModifiedDate":"2026-08-17 06:19:53","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"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","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"74556","Ordinal":"1","Title":"scsi: libiscsi_tcp: Bound SCSI Response data segment to the conn","CVE":"CVE-2026-74556","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"74556","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"scsi: libiscsi_tcp: Bound SCSI Response data segment to the conn"}]}}}