CVE-2026-74556 is a vulnerability in Linux Kernel
Published on August 15, 2026
scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer
In the Linux kernel, the following vulnerability has been resolved:
scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer
iscsi_tcp_hdr_dissect() receives the data segment of several PDU types
into the fixed-size conn->data buffer, which is allocated for
ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes. For the LOGIN_RSP, TEXT_RSP,
REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU
whose DataSegmentLength exceeds that buffer.
The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its
data segment (sense/response data) into conn->data via
iscsi_tcp_data_recv_prep(), but it does so without the same check. The
only upstream bound on in.datalen is conn->max_recv_dlength, the
initiator's advertised MaxRecvDataSegmentLength, which is commonly
negotiated well above 8192 (open-iscsi defaults to 262144). A target
that returns a SCSI Response with a DataSegmentLength between 8193 and
max_recv_dlength therefore overflows the 8192-byte conn->data buffer.
Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly
like those responses: bound the data segment, receive it into conn->data
when present, and otherwise complete the PDU with no data. Fold the
opcode into that case group rather than duplicating the check.
Products Associated with CVE-2026-74556
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Affected Versions
Linux:- Version a081c13e39b5c17052a7b46fafa61019c4c110ff and below c97b5265cc47775f77fd2a23d6bde0426997b233 is affected.
- Version a081c13e39b5c17052a7b46fafa61019c4c110ff and below 084af0253673425ce2ae62e3c7f74f0dd023711b is affected.
- Version a081c13e39b5c17052a7b46fafa61019c4c110ff and below 72815741715bd41556dac5eeb068bf0f8af06ee7 is affected.
- Version a081c13e39b5c17052a7b46fafa61019c4c110ff and below b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676 is affected.
- Version a081c13e39b5c17052a7b46fafa61019c4c110ff and below c1dea15f819cded9b3faf58f8bec72323568b6e6 is affected.
- Version 2.6.29 is affected.
- Before 2.6.29 is unaffected.
- Version 6.6.151, <= 6.6.* is unaffected.
- Version 6.12.103, <= 6.12.* is unaffected.
- Version 6.18.44, <= 6.18.* is unaffected.
- Version 7.1.8, <= 7.1.* is unaffected.
- Version 7.2-rc6, <= * is unaffected.