---
id: "CVE-2026-99152"
kind: "vulnerability"
aliases: ["CVE-2026-99152"]
title: "Linux kernel iSCSI: unsolicited target response crashes the host with a null dereference"
severity: "high"
cvss: null
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["infrastructure", "iscsi", "kernel", "linux", "storage"]
not_affected_if: ["kernel-without-libiscsi", "no-iscsi-sessions"]
published_at: "2026-10-28T11:17:35+00:00"
first_seen_at: "2026-10-28T11:32:35+00:00"
updated_at: "2026-10-28T11:35:55+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99152", "first_seen_at": "2026-10-28T11:32:35+00:00"}]
---

# Linux kernel iSCSI: unsolicited target response crashes the host with a null dereference

The Linux kernel's libiscsi accepts a management response that names an unused task slot, then dereferences a null connection pointer. A malicious or compromised iSCSI target can send one unsolicited NOP-In or Text Response and crash the initiator kernel.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `uname -r` and compare against the fixed kernel builds listed by your distribution
- Check whether the iSCSI initiator is loaded with `lsmod | grep -E 'libiscsi|iscsi_tcp'`
- Confirm the host uses iSCSI sessions to targets with `iscsiadm -m session`

## Fix

- Update the Linux kernel to a release that includes the libiscsi fix (the upstream commit 'scsi: libiscsi: Validate the task named by a management response'); the sources do not name a fixed version
- Reboot after the kernel update so the patched module is running

## Timeline

- 2026-10-28T11:32:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99152

## From the sources

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

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_