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CVE-2026-72099
dm-integrity: don't increment hash_offset twice
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-2026-72099 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 | fixedDLA-4777-1 · 2026-09-08 · text | 6.1.187-1 | Update the kernel and reboot. DLA-4777-1 shipped the fix on 2026-09-08, in 6.1.187-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| 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
hash_offset is already incremented in the loop "for (i = 0; i < to_copy; i++, ts--)". Do not increment it again.
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/dm-integrity.c
- What this is
- DEVICE-MAPPER (LVM)MAINTAINERS section matched on drivers/md/dm* · dm-devel@lists.linux.dev · Maintained
- Kernel module
- dm_integrity
Check it on the machine
grep -wE 'CONFIG_DM_INTEGRITY|CONFIG_MD' /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 dm_integrityPrints 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_DM_INTEGRITY, CONFIG_MD
- 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:H/A:Lsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.55%, higher than 44.6% 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 |
|---|---|---|
| 5.7 | 5.10.266 | c66b1781a549 |
| 5.7 | 5.15.217 | 39697e2759ac |
| 5.7 | 6.1.184 | e6646f4d711d |
| 5.7 | 6.6.145 | cf9feed8c131 |
| 5.7 | 6.12.97 | 4f4e43337e9e |
| 5.7 | 6.18.40 | 5dfd80426352 |
| 5.7 | 7.1.5 | 829476c06496 |
| 5.7 | 7.2 | edf025f08385 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4777-1 | 2026-09-08 | bookworm 6.1.187-1 | 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 flaw is reached via block I/O on dm-integrity journal/bitmap targets; in enterprise/cloud deployments those volumes are commonly accessed remotely through NFS/ksmbd file exports or iSCSI/NVMe-oF/NBD block protocols, letting a remote client drive the vulnerable TAG_CMP path.
- AC:LAttack complexity, low
- An attacker with read access can reliably trigger TAG_CMP by issuing ordinary multi-sector reads; when metadata tag comparisons span dm-bufio buffer boundaries the double-incremented hash_offset mispredicts tag boundaries without races or uncontrollable layout.
- PR:LPrivileges required, low
- Table creation needs CAP_SYS_ADMIN (obtainable in a user namespace), but exploitation only requires read/write access to the mapped block device or an exported filesystem backed by it, not init-namespace root.
- UI:NUser interaction, none
- Exploitation requires only attacker-initiated reads or writes against the dm-integrity-backed storage; no additional victim actions such as mounting a filesystem or opening files beyond the attacker's own I/O are needed.
- S:UScope, unchanged
- Impact is incorrect integrity-tag verification within the host kernel's device-mapper layer, enabling undetected data tampering or spurious verification failures on the same host; it does not cross VM, container, or IOMMU security boundaries.
- C:NConfidentiality impact, none
- The bug corrupts tag-boundary state during comparison but does not cause kernel memory disclosure, out-of-bounds reads, or use-after-free; any wrong data returned is attacker-supplied disk content, not leakage of unrelated kernel or user secrets.
- I:HIntegrity impact, high
- Misaligned hash_offset can accept integrity tags that should fail verification (including mixed hash/discard-filler boundaries), defeating dm-integrity's tamper detection and allowing undetected modification of protected block data.
- A:LAvailability impact, low
- The same logic error can spuriously fail checksum verification on legitimate reads, returning I/O errors and denying access to protected data without kernel panic, though repeated reads can sustain a denial-of-service against the volume.