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CVE-2026-72107
dm era: fix out-of-bounds memory access for non-zero start sector
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-2026-72107 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 | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. 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
dm-era tracks writes in target-relative blocks, but era_map() calculates the writeset block before applying the target offset. Tables with a non-zero start sector can therefore pass an absolute mapped-device block to metadata_current_marked(). If the absolute block is beyond the current writeset size, writeset_marked() tests past the end of the in-core bitset. KASAN reports this as a vmalloc-out-of-bounds access. Apply the target offset before calculating the era block so writeset lookups use the target-relative block number.
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-era-target.c
- What this is
- DEVICE-MAPPER (LVM)MAINTAINERS section matched on drivers/md/dm* · dm-devel@lists.linux.dev · Maintained
- Kernel module
- dm_era
Check it on the machine
grep -wE 'CONFIG_DM_ERA|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_eraPrints 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_ERA, 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
- 8.8 high
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- network (AV:N)source
- EPSS
- 0.65%, higher than 50.2% 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 |
|---|---|---|
| 3.15 | 5.10.261 | fe94a0b14010 |
| 3.15 | 5.15.212 | e3ffa8e492e5 |
| 3.15 | 6.1.178 | 9946a7176bd8 |
| 3.15 | 6.6.145 | 7e1822f83c5a |
| 3.15 | 6.12.97 | db5f9b4601f0 |
| 3.15 | 6.18.40 | 1fcb5e29dd7a |
| 3.15 | 7.1.5 | bafe3e720cda |
| 3.15 | 7.2 | a868196f03c2 |
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 hit in era_map() on write bios submitted to a dm-era device; on storage servers that expose dm-era-backed LUNs via iSCSI or NVMe-oF, a remote initiator's SCSI/NVMe writes traverse the network stack into dm_submit_bio() and reach the flawed writeset lookup without local shell access.
- AC:LAttack complexity, low
- Once a dm-era table uses a non-zero start sector (common when mapping a partition offset), any single write I/O deterministically passes an out-of-range block index to writeset_marked()/test_bit(); no race, special heap layout, or victim state beyond that configuration is required.
- PR:LPrivileges required, low
- Exploitation requires only write access to the dm-era-backed block device (filesystem, raw /dev/dm-* node, or authenticated iSCSI/NVMe-oF initiator credentials); loading the dm table needs CAP_SYS_ADMIN, but triggering the OOB read does not—unprivileged local users or remote storage clients with write permission suffice.
- UI:NUser interaction, none
- Triggering the flaw requires only the attacker's own write I/O to the dm-era volume; no victim must mount a filesystem, open a file, click a link, or perform any separate interactive action beyond routine storage writes.
- S:UScope, unchanged
- The vmalloc out-of-bounds read and any resulting kernel oops or privilege escalation occur entirely within the host kernel's device-mapper/storage subsystem on the same machine; this is not a VM escape, IOMMU bypass, or other cross-security-authority boundary violation.
- C:HConfidentiality impact, high
- writeset_marked() calls test_bit() with an attacker-influenced block index derived from the write offset; when the absolute block exceeds the writeset size this is a vmalloc out-of-bounds read that can disclose adjacent kernel heap memory, matching CNA guidance for OOB reads.
- I:HIntegrity impact, high
- Kernel vmalloc out-of-bounds access via test_bit() is memory corruption in a privileged context; disclosed adjacent heap contents can be used to craft follow-on arbitrary-write or control-flow hijack primitives, so integrity impact is rated High when uncertain between Low and High.
- A:HAvailability impact, high
- KASAN reports this as vmalloc-out-of-bounds, and reading past the vzalloc'd bitset can fault on unmapped pages or provoke a kernel oops/panic, causing immediate denial of service on storage nodes processing writes through dm-era.