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CVE-2026-72440
md/raid1: fix writes_pending and barrier reference leaks on write failures
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem drivers/md. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-72440 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 | vulnerable | 6.1.190-1 | No fix published anywhere yet, neither in Debian nor upstream for the series bookworm tracks. Watch the Debian tracker page for this CVE. Advisories for bookworm have historically landed a median of 23 days after publication. |
| Debian 13trixie | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
raid1_make_request() acquires a writes_pending reference with md_write_start() before calling raid1_write_request(). Several failure paths in raid1_write_request() complete the bio and return without reaching the normal write completion path, causing the corresponding md_write_end() to be skipped. Make raid1_write_request() return a status indicating whether the write request was successfully queued. This allows raid1_make_request() to call md_write_end() when raid1_write_request() fails. Additionally, if wait_blocked_rdev() fails after wait_barrier() succeeds, the associated barrier reference is not released. Call allow_barrier() before returning from that path to keep the barrier accounting balanced.
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/md/raid1.c
- What this is
- SOFTWARE RAID (Multiple Disks) SUPPORTMAINTAINERS section matched on drivers/md/raid* · linux-raid@vger.kernel.org · Supported
- Kernel module
- raid1
Check it on the machine
grep -wE 'CONFIG_MD|CONFIG_MD_RAID1' /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 raid1Prints 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, sidm
- m
- a loadable module on every flavour - check lsmod, can be blacklisted
- Build switches
- CONFIG_MD, CONFIG_MD_RAID1
- 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
- 2026-08-15 (2 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.46%, higher than 38.8% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- drivers/md
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 5.17 | 6.18.57 | 7a4504606879 |
| 5.17 | 7.1.5 | bffbbfcbd939 |
| 5.17 | 7.2 | 8e065a160251 |
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 in md/raid1 write handling reached via block-layer writes to RAID1-backed volumes; on storage servers and appliances, remote NFS, SMB (ksmbd), iSCSI, and NVMe-oF clients submit those writes through md_submit_bio() to raid1_make_request() the same as local I/O.
- AC:LAttack complexity, low
- An attacker with write access can reliably trigger the leaks using RWF_NOWAIT during active resync/barriers, against mirrors in BlockedBadBlocks state after prior write errors, or via bio_submit_split_bioset() failure paths; they control I/O timing and concurrency without uncontrollable races.
- PR:LPrivileges required, low
- Exploitation requires only the ability to issue writes to the RAID1 array—via a mounted filesystem, O_RDWR on /dev/mdX, or an authenticated network storage client—not CAP_SYS_ADMIN or other privileges needed to create or reconfigure the md array.
- UI:NUser interaction, none
- No victim interaction is required; the attacker or their storage client issues the triggering RWF_NOWAIT or failing write requests directly, with no separate mount, file open, or administrator action needed at exploitation time.
- S:UScope, unchanged
- Impact is confined to kernel md RAID1 write/barrier accounting and array lifecycle state within the same host kernel; it does not cross VM, container, or IOMMU security boundaries.
- C:NConfidentiality impact, none
- Leaked writes_pending and nr_pending reference counters do not corrupt memory, read out of bounds, or use-after-free; there is no kernel pointer leak or arbitrary memory disclosure primitive.
- I:LIntegrity impact, low
- Skipped md_write_end() on failure paths leaves writes_pending inflated and prevents set_in_sync()/clean sysfs transitions, causing persistent incorrect RAID1 dirty/clean metadata state that cannot be corrected until reboot.
- A:HAvailability impact, high
- Leaked conf->nr_pending from the wait_blocked_rdev()+REQ_NOWAIT path inflates get_unqueued_pending() so freeze_array() wait_event never completes, deadlocking array quiesce, reshape, removal, and read-error recovery while array_frozen blocks new I/O.