Bug 2517034 (CVE-2026-74557)

Summary: CVE-2026-74557 kernel: scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's libiscsi component. An incorrect bounds check in the `iscsi_scsi_cmd_rsp()` function allows a malicious iSCSI target to craft a SCSI Response. This can lead to a read beyond the intended buffer, causing stale connection data to be copied into the SCSI sense buffer and subsequently returned to userspace, potentially disclosing sensitive information.
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Description OSIDB Bzimport 2026-08-15 12:46:05 UTC 
In the Linux kernel, the following vulnerability has been resolved:

scsi: libiscsi: Fix stale-data leak into the SCSI sense buffer

iscsi_scsi_cmd_rsp() copies the sense data of a SCSI Response from the
target-supplied data segment.  The segment carries a 2-byte sense length
followed by the sense bytes, so it must hold 2 + senselen bytes, but the
bounds check only requires datalen >= senselen:

	senselen = get_unaligned_be16(data);
	if (datalen < senselen)
		goto invalid_datalen;
	memcpy(sc->sense_buffer, data + 2,
	       min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));

A target that returns a SCSI Response whose datalen equals senselen
(with senselen <= SCSI_SENSE_BUFFERSIZE) makes the memcpy() from data +
2 read up to two bytes past the received data.  Those bytes are stale
conn->data contents and end up in the command's sense buffer, which is
returned to userspace.

Account for the 2-byte sense length prefix in the check.
Comment 1 Mauro Matteo Cascella 2026-08-19 18:38:31 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081551-CVE-2026-74557-6742@gregkh/T