CVE-2026-98479

Received Received - Intake

Linux Kernel Data-In PDU Direction Validation Flaw

Publication date: 2026-10-18

Last updated on: 2026-10-19

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi_tcp: Check the data direction of a Data-In PDU The Data-In branch of iscsi_tcp_hdr_dissect() resolves the ITT to a task and copies the PDU's data segment into that command's scatterlist without asking whether the command was reading. iscsi_tcp_r2t_rsp() in the same file does ask, and rejects an R2T for a command that is not DMA_TO_DEVICE. A target that answers a WRITE command's ITT with a Data-In therefore has the initiator write target-supplied bytes into the pages that write was about to send. Those are the caller's own pinned pages for an O_DIRECT write, and page cache pages for a buffered one. Observed against a test target that emits one 512-byte Data-In naming a 128 KB write's ITT, after the R2T for that write. With O_DIRECT the caller's buffer ends up holding 512 bytes of the target's data while pwrite() returns 131072. Buffered is quieter: pwrite() and fsync() both succeed, nothing is logged, and reading those blocks back returns the target's bytes out of the page cache without a command going on the wire. Check the direction before using the scatterlist, the way the R2T path already does.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-10-18

Last Modified

2026-10-19

Generated

2026-10-19

AI Q&A

2026-10-18

EPSS Evaluated

N/A

NVD

CVE-2026-98479

EUVD

EUVD-2026-103719

Affected Vendors & Products

Vendor	Product	Version / Range
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	a081c13e39b5c17052a7b46fafa61019c4c110ff
Linux	Linux	2.6.29

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves the iSCSI TCP implementation incorrectly handling Data-In PDUs for WRITE commands. The system fails to verify if a command is reading data before copying target-supplied bytes into the command's scatterlist. This allows a malicious iSCSI target to write arbitrary data into the initiator's memory pages, potentially overwriting intended data.

Detection Guidance

This vulnerability affects the Linux kernel's iSCSI TCP implementation. Detection requires checking kernel logs for unusual iSCSI activity or verifying kernel version against patched releases. No specific commands are provided in the context.

Impact Analysis

An attacker controlling an iSCSI target could exploit this to corrupt data on your system. For O_DIRECT writes, the attacker's data would overwrite your buffer directly. For buffered writes, the page cache could be silently corrupted, leading to incorrect data being read back later without any error indication.

Compliance Impact

This vulnerability could potentially violate compliance with GDPR and HIPAA by allowing unauthorized data writes to memory regions during iSCSI operations. It enables a target to overwrite the initiator's data buffers, which may lead to data corruption or unauthorized data exposure, compromising data integrity and confidentiality.

Mitigation Strategies

Apply the Linux kernel patch that resolves this issue. Update to a patched kernel version where the Data-In branch checks data direction before processing. Monitor iSCSI logs for suspicious activity.

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