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CVE-2026-80691
scsi: target: iblock: Fix wrong PR ops NULL check for PREEMPT/RELEASE
Published 2026-08-28 (2 months ago) by the Linux kernel CNA. Subsystem drivers/target. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-80691 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.105-1 | Update the kernel and reboot. Fixed in 6.12.105-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.8-1 | Update the kernel and reboot. Fixed in 7.1.8-1. A running kernel keeps the old code until the machine restarts. |
| Debian 12bookworm · linux-6.12 | fixedDLA-4788-1 · 2026-09-19 · text | 6.12.107-1~deb12u1 | Update the kernel and reboot. DLA-4788-1 shipped the fix on 2026-09-19, in 6.12.107-1~deb12u1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
In the iblock_execute_pr_out() function, PRO_PREEMPT, PRO_PREEMPT_AND_ABORT, and PRO_RELEASE all perform callback capability checks through ops->pr_clear. The error check allows unimplemented hooks to pass through the gate, resulting dereferencing a NULL function pointer. Check whether the hooks that need to be called are supported.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
drivers/target/target_core_iblock.c
- What this is
- SCSI TARGET SUBSYSTEMMAINTAINERS section matched on drivers/target/ · linux-scsi@vger.kernel.org · Supported
- Kernel module
- target_core_iblock
Check it on the machine
grep -wE 'CONFIG_TARGET_CORE|CONFIG_TCM_IBLOCK' /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
lsmod | grep -w target_core_iblockPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this as a loadable module. Every release below compiles it as a module on every flavour, so whether the code is in the running kernel depends on whether that module is loaded.
- bookworm, trixie, forky, sid, bookworm · linux-6.12m
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_TARGET_CORE, CONFIG_TCM_IBLOCK
- Reads as
- all on means the file is compiled; any one off means it is not.
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-28 (2 months ago)source
- CVSS
- 7.5 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.44%, higher than 36.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- drivers/target
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.5 | 6.6.151 | 3c60a8b4037d |
| 6.5 | 6.12.103 | a326b19cfb77 |
| 6.5 | 6.18.44 | bdd8a1297ef1 |
| 6.5 | 7.1.8 | f15bcf9a99b1 |
| 6.5 | 7.2 | 9c33222bd387 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4788-1 | 2026-09-19 | bookworm 6.12.107-1~deb12u1 | tracker |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:NAttack vector, network
- The bug is reached when a remote SCSI initiator sends PERSISTENT RESERVE OUT (PRO_PREEMPT, PRO_PREEMPT_AND_ABORT, or PRO_RELEASE) to a LIO target exporting an iblock LUN over iSCSI/FC/IB fabrics; iscsit_handle_scsi_cmd() drives transport_generic_new_cmd() to target_scsi3_emulate_pr_out() and iblock_execute_pr_out() without local shell access.
- AC:LAttack complexity, low
- After an admin enables iblock PR passthrough (TRANSPORT_FLAG_PASSTHROUGH_PGR) on a backing block device with pr_ops, any authenticated or misconfigured unauthenticated initiator can deterministically issue the affected SCSI service actions; no races or victim timing are required beyond normal target I/O.
- PR:NPrivileges required, none
- Exploitation requires only the ability to complete an iSCSI (or equivalent fabric) login and submit SCSI commands to the exposed LUN; it does not require Linux UID, capabilities, or root on the target host, and targets are often deployed with authentication disabled or open demo ACLs.
- UI:NUser interaction, none
- No interactive victim action is needed; the attacker triggers the NULL function-pointer dereference solely by sending a crafted PERSISTENT RESERVE OUT CDB and 24-byte parameter list over the storage network protocol.
- S:UScope, unchanged
- Impact is a kernel oops/panic on the storage target host running LIO; it does not cross VM, container, or IOMMU boundaries and stays within the kernel's single security authority.
- C:NConfidentiality impact, none
- The failure is a direct NULL function-pointer call (ops->pr_preempt or ops->pr_release) when the wrong pr_clear guard passes; this causes an immediate kernel fault with no out-of-bounds read, use-after-free, or attacker-controlled memory disclosure primitive.
- I:NIntegrity impact, none
- The bug does not modify user data, on-disk metadata, or kernel memory contents; it only attempts to invoke a missing callback and crashes, providing no arbitrary write or code-execution primitive beyond the fault itself.
- A:HAvailability impact, high
- Dereferencing a NULL block-layer PR callback from kernel context causes an oops or panic on the target server, denying all storage services hosted on that node until reboot and potentially taking down co-located workloads.