Critical severity · published Aug 15, 2026
CVE-2026-74556
scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer
9.8
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
a081c13e39b5c17052a7b46fafa61019c4c110ff before a51812842084fd390590ab8dc0431f10c73ddc56; a081c13e39b5c17052a7b46fafa61019c4c110ff before a8f94cc9f0e5759252551be3a172960c57f21f54; a081c13e39b5c17052a7b46fafa61019c4c110ff before f1a3a51fc5dba0e99532379665069f1700da6b44; a081c13e39b5c17052a7b46fafa61019c4c110ff before c97b5265cc47775f77fd2a23d6bde0426997b233; a081c13e39b5c17052a7b46fafa61019c4c110ff before 084af0253673425ce2ae62e3c7f74f0dd023711b; a081c13e39b5c17052a7b46fafa61019c4c110ff before 72815741715bd41556dac5eeb068bf0f8af06ee7; +3 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-74556
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-74556
git.kernel.org
https://git.kernel.org/stable/c/084af0253673425ce2ae62e3c7f74f0dd023711b
git.kernel.org
https://git.kernel.org/stable/c/72815741715bd41556dac5eeb068bf0f8af06ee7
git.kernel.org
https://git.kernel.org/stable/c/a51812842084fd390590ab8dc0431f10c73ddc56
git.kernel.org
https://git.kernel.org/stable/c/a8f94cc9f0e5759252551be3a172960c57f21f54
git.kernel.org
https://git.kernel.org/stable/c/b0aa3e8e2ab4ca92adb28a3ef41873b3363b8676
git.kernel.org
https://git.kernel.org/stable/c/c1dea15f819cded9b3faf58f8bec72323568b6e6
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