CVE-2026-99152

None

CVSS

—

EPSS

0.2%

Published

Oct 28, 2026

CISA due date

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Cloudanix analysis

Next patch cycle SSVC: Track

A recently disclosed flaw in the Linux kernel can let a malicious storage server crash the computer by sending one unexpected reply, interrupting any work that relies on network storage.

Exploitation: Remote Authenticated
Attacker needs: Low Privilege
Complexity: Low
Impact: Denial Of Service
Component: OS kernel
Class: Memory Corruption
Remediation: Upgrade
Effort: Medium
Patch risk: Low

What it actually does

Null pointer dereference in libiscsi when __iscsi_complete_pdu processes management responses (LOGOUT_RSP, LOGIN_RSP, TEXT_RSP, TMFUNC_RSP, NOOP_IN) by calling iscsi_itt_to_task without verifying the task is in flight; an invalid ITT yields a slot whose task->conn is NULL, which is dereferenced in iscsi_nop_out_rsp and iscsi_complete_task.

Why it matters to the business

Systems using Linux iSCSI initiators can experience immediate kernel crashes from a single malicious response, resulting in denial of service and potential data unavailability for storage workloads; the flaw was published one day ago with no known exploitation yet.

How an attack unfolds

An attacker who controls an iSCSI target sends an unsolicited NOP-In or Text Response PDU containing an ITT that indexes an unused command slot; the kernel resolves a non-null task pointer whose conn field is NULL and immediately dereferences it, triggering a general protection fault or KASAN null-ptr-deref.

How to fix it

Apply the upstream fix that adds an in-flight and non-SCSI-command check equivalent to iscsi_itt_to_ctask before using the resolved task; monitor distribution kernel updates that backport the change and reboot after installation.

How to confirm the fix worked

Confirm the running kernel contains the commit that adds the in-flight validation in __iscsi_complete_pdu; reproduce the crash path in a test environment and verify the oops no longer occurs on receipt of an out-of-range ITT.

Typical attack path

Establish iSCSI session from vulnerable Linux initiator to attacker-controlled target
Send management response (NOP-In or Text Response) with ITT referencing an unused task slot
Kernel performs iscsi_itt_to_task lookup and skips further validation
iscsi_nop_out_rsp or iscsi_complete_task dereferences NULL task->conn
Kernel oops and panic occurs

How to detect it

Search kernel logs and dmesg for oops messages referencing iscsi_nop_out_rsp, iscsi_complete_task, or __iscsi_complete_pdu together with null-ptr-deref or general protection fault at non-canonical addresses; correlate with iSCSI TCP receive paths.

iscsi_nop_out_rsp.constprop.0+0x46
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
__iscsi_complete_pdu+0x13a8
general protection fault, probably for non-canonical address

What your security team should do

Prioritize kernel updates for all Linux hosts that use iSCSI initiators
Restrict iSCSI targets to trusted endpoints until patches are deployed
Enable kernel panic logging and monitoring for iSCSI-related oops signatures
Review iSCSI session logs for unexpected management responses after patching

The record

In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi: Validate the task named by a management response __iscsi_complete_pdu() fetches the task for five response types from one place and checks only that the index resolved: case ISCSI_OP_LOGOUT_RSP: case ISCSI_OP_LOGIN_RSP: case ISCSI_OP_TEXT_RSP: case ISCSI_OP_SCSI_TMFUNC_RSP: case ISCSI_OP_NOOP_IN: task = iscsi_itt_to_task(conn, hdr->itt); if (!task) return ISCSI_ERR_BAD_ITT; iscsi_itt_to_task() bounds the index against cmds_max and looks at nothing else, so a target can name any slot in the pool, including one that has never been used. task->conn is then NULL, and both iscsi_nop_out_rsp() and iscsi_complete_task() dereference it. One unsolicited NOP-In is enough; a Text Response carrying the same ITT crashes in iscsi_complete_task() instead. Require the task to be in flight and not a SCSI command, the way iscsi_itt_to_ctask() does for the command opcodes. [ 6.298634] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI [ 6.298642] KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067] [ 6.298652] CPU: 1 UID: 0 PID: 111 Comm: iscsistart Not tainted 7.2.0-rc5-ISCSI1-gf5098b6bae76 #1 PREEMPT(lazy) [ 6.298654] 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 [ 6.298656] RIP: 0010:iscsi_nop_out_rsp.constprop.0+0x46/0x160 [ 6.298691] 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 [ 6.298698] RSP: 0018:ffff88806c907be8 EFLAGS: 00010206 [ 6.298701] RAX: dffffc0000000000 RBX: ffff888006116800 RCX: 0000000000000020 [ 6.298702] RDX: 000000000000000c RSI: ffff88800525d578 RDI: 0000000000000060 [ 6.298703] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 6.298706] R10: 0000000000000020 R11: 0000000000000000 R12: 0000000000000000 [ 6.298706] R13: 000000000000002e R14: ffff8880056eb440 R15: ffff888006116800 [ 6.298707] FS: 00007fc02d1c2740(0000) GS:ffff8880b29bc000(0000) knlGS:0000000000000000 [ 6.298710] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 6.298711] CR2: 000055fe3b56ddf8 CR3: 00000000053b9004 CR4: 0000000000770ef0 [ 6.298712] PKRU: 55555554 [ 6.298713] Call Trace: [ 6.298714] <IRQ> [ 6.298714] __iscsi_complete_pdu+0x13a8/0x22a0 [ 6.298758] iscsi_complete_pdu+0x54/0xa0 [ 6.298759] iscsi_tcp_hdr_recv_done+0x870/0x2c80 [ 6.298778] iscsi_tcp_recv_skb+0x31e/0xec0 [ 6.298800] iscsi_sw_tcp_recv+0x12f/0x390 [ 6.298804] __tcp_read_sock+0x1ab/0x810 [ 6.298812] iscsi_sw_tcp_data_ready+0x18b/0x510 [ 6.298814] tcp_rcv_established+0x1f56/0x3a00 [ 6.298842] tcp_v4_do_rcv+0x449/0x960 [ 6.298847] tcp_v4_rcv+0x2245/0x3bc0

Affected packages

Ecosystem	Package	Introduced	Fixed