CVE-2026-99153
Received Received - Intake

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Vulnerability report for CVE-2026-99153, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-10-28

Last updated on: 2026-10-28

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi: Validate the ITT reflected in a Reject PDU A Reject PDU carries a copy of the header it rejects, and iscsi_handle_reject() takes the ITT out of that copy to find the task to clean up: memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr)); ... task = iscsi_itt_to_task(conn, rejected_pdu.itt); That value is whatever the target put there. iscsi_itt_to_task() bounds the index against cmds_max and checks nothing else, so any task in the pool can be named, and iscsi_nop_out_rsp() then completes it. An index that has never been used gives a NULL task->conn: the pool is zeroed at session setup and conn is assigned only when a task is allocated. If the task was used and returned, iscsi_complete_task() hits its WARN_ON_ONCE(task->state == ISCSI_TASK_FREE) and the refcount underflows. An in-flight SCSI command is completed as successful - a 1 MiB read returned 1048576 with none of its buffer written and no warning. Validate the reflected ITT the way iscsi_itt_to_ctask() validates a command ITT, and require the task to be in flight and not a SCSI command. [ 6.248477] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI [ 6.249357] KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067] [ 6.249951] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 7.2.0-rc5-ISCSI1-gf5098b6bae76 #1 PREEMPT(lazy) [ 6.250718] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 6.251616] RIP: 0010:iscsi_nop_out_rsp.constprop.0+0x46/0x160 [ 6.252043] Code: c1 ea 03 48 83 ec 08 80 3c 02 00 0f 85 f5 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 58 48 8d 7d 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 00 00 00 48 8b 45 60 48 39 c3 74 50 48 b8 00 [ 6.252813] RSP: 0018:ffff88806c907b80 EFLAGS: 00010206 [ 6.253042] RAX: dffffc0000000000 RBX: ffff88800607e000 RCX: ffffffff8d571a25 [ 6.253345] RDX: 000000000000000c RSI: ffff88806c907c38 RDI: 0000000000000060 [ 6.253642] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff235a504 [ 6.253947] R10: 0000000000000003 R11: 7463656e6e6f6320 R12: 0000000000000000 [ 6.254251] R13: 0000000000000000 R14: ffff88806c907c38 R15: 0000000000000000 [ 6.254549] FS: 0000000000000000(0000) GS:ffff8880d95bc000(0000) knlGS:0000000000000000 [ 6.254887] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6.255140] CR2: 00007fc393e8ffc0 CR3: 0000000005252006 CR4: 0000000000770ef0 [ 6.255439] PKRU: 55555554 [ 6.255564] Call Trace: [ 6.255674] <IRQ> [ 6.255768] __iscsi_complete_pdu+0x18bf/0x22a0 [ 6.256733] iscsi_complete_pdu+0x54/0xa0 [ 6.256905] iscsi_tcp_data_recv_done+0xf4/0x250 [ 6.257103] iscsi_tcp_recv_skb+0x31e/0xec0 [ 6.257680] iscsi_sw_tcp_recv+0x12f/0x390 [ 6.258061] __tcp_read_sock+0x1ab/0x810 [ 6.258853] iscsi_sw_tcp_data_ready+0x18b/0x510 [ 6.259808] tcp_data_queue+0x1f13/0x4cd0 [ 6.260567] tcp_rcv_established+0x8a5/0x3a00 [ 6.261931] tcp_v4_do_rcv+0x449/0x960 [ 6.262269] tcp_v4_rcv+0x2245/0x3bc0

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Meta Information

Published
2026-10-28
Last Modified
2026-10-28
Generated
2026-10-28
AI Q&A
2026-10-28
EPSS Evaluated
N/A
NVD
EUVD

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
Linux Linux 8afa1439fcff58da8f28c1d083046f229f6ab3de
Linux Linux 8afa1439fcff58da8f28c1d083046f229f6ab3de
Linux Linux 8afa1439fcff58da8f28c1d083046f229f6ab3de
Linux Linux 2.6.32

Helpful Resources

Exploitability

CWE
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel's iSCSI subsystem allows a remote attacker to manipulate the iSCSI target to send a Reject PDU with a crafted ITT (Initiator Task Tag) that points to an arbitrary task in the task pool. This can lead to memory corruption, null pointer dereferences, or even completion of arbitrary SCSI commands as successful without data transfer.

Detection Guidance

This vulnerability affects the Linux kernel's iSCSI subsystem. Detection requires checking kernel logs for general protection faults or null-ptr-deref errors related to iscsi_nop_out_rsp. Monitor system logs for crashes or kernel oopses involving iSCSI tasks.

Impact Analysis

An attacker could exploit this to crash the system via a kernel oops, corrupt memory, or cause a refcount underflow. In the worst case, it might allow unauthorized completion of SCSI commands, leading to data corruption or unauthorized access to data.

Mitigation Strategies

Apply the latest Linux kernel patches that address this issue. If patches are unavailable, disable the iSCSI target functionality until updates are applied. Monitor vendor advisories for kernel updates addressing CVE-2026-99153.

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