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NVD / CVE Program· CNA Linux

CVE-2026-72108: dm thin metadata: fix metadata snapshot consistency on commit failure

Noroxi assessment

Priority: Monitor (action score 31/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 3dc9ae1029320d77472c44965e572f176949cd63, 4af993468193cf4cd32ba5748786e7801945f7d2, 5bcd4d3058ebaf46ad2e163829d87dd4870c7a45.

Low priority for now. Upgrade to Linux Linux 3dc9ae1029320d77472c44965e572f176949cd63, 4af993468193cf4cd32ba5748786e7801945f7d2, 5bcd4d3058ebaf46ad2e163829d87dd4870c7a45 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: dm thin metadata: fix metadata snapshot consistency on commit failure __reserve_metadata_snap() and __release_metadata_snap() modify the superblock's held_root directly in the block_manager's buffer. If the subsequent metadata commit fails, the held_root gets flushed to disk through the abort_transaction path, resulting in inconsistent metadata. Reproducer 1: __reserve_metadata_snap() 1. Create a 2 MiB metadata device and make the region after the 14th block inaccessible, to trigger metadata commit failure in the subsequent reserve_metadata_snap operation. The 14th block will be the shadow destination for the index block. dmsetup create tmeta --table "0 112 linear /dev/sdc 0 112 3984 error" 2. Create a 16 MiB thin-pool dmsetup create tdata --table "0 32768 zero" dd if=/dev/zero of=/dev/mapper/tmeta bs=4k count=1 dmsetup create tpool --table "0 32768 thin-pool /dev/mapper/tmeta \ /dev/mapper/tdata 128 0 1 skip_block_zeroing" 3. Take a metadata snapshot to trigger metadata commit failure and transaction abort. However, the held_root is written to disk, breaking metadata consistency. dmsetup message tpool 0 "reserve_metadata_snap" thin_check v1.2.2 result: Bad reference count for metadata block 6. Expected 2, but space map contains 1. Bad reference count for metadata block 7. Expected 2, but space map contains 1. Bad reference count for metadata block 13. Expected 1, but space map contains 0. Reproducer 2: __release_metadata_snap() 1. Create a 2 MiB metadata device and make the region after the 16th block inaccessible, to trigger metadata commit failure in the subsequent release_metadata_snap operation. The 16th block will be the shadow destination for the index block. dmsetup create tmeta --table "0 128 linear /dev/sdc 0 128 3968 error" 2. Create a 16 MiB thin-pool dmsetup create tdata --table "0 32768 zero" dd if=/dev/zero of=/dev/mapper/tmeta bs=4k count=1 dmsetup create tpool --table "0 32768 thin-pool /dev/mapper/tmeta \ /dev/mapper/tdata 128 0 1 skip_block_zeroing" 3. Reserve then release the metadata snapshot, to trigger metadata commit failure and transaction abort. The held_root gets removed from the on-disk superblock, causing inconsistent metadata. dmsetup message tpool 0 "reserve_metadata_snap" dmsetup message tpool 0 "release_metadata_snap" thin_check v1.2.2 result: Bad reference count for metadata block 6. Expected 1, but space map contains 2. Bad reference count for metadata block 7. Expected 1, but space map contains 2. 1 metadata blocks have leaked. Fix by deferring the held_root update to commit time. Additionally, move the existing-snapshot check in __reserve_metadata_snap before the shadow operation to avoid unnecessary work. In __release_metadata_snap, clear pmd->held_root before btree deletion so partial failure leaks blocks rather than leaving a stale reference, and unlock the snapshot block before decrementing its refcount.

HighCVSS 7.8 · v3.1—No exploit Fix available
Published
Aug 15, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 17th percentile

Report tools

JSON

Action score

31

Monitor

Low priority for now.

CVSS
31 / 40 · 7.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 3.2affected
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 4af993468193cf4cd32ba5748786e7801945f7d2affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before abf2fae92cbe68945028987d498cc72f8f0e23a8affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 5efb1a7734ed4035fa4fdc3716bdb84621f27cf6affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 3dc9ae1029320d77472c44965e572f176949cd63affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before b5f9a31c51cbb374a1713c3494f8660ab070f035affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 7f76245960a332f39b08cc556e675d1765dc5bbbaffected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 9f1a0d27586ceab055e6b050e3731ce3c6b2c4f0affected · git
    • 991d9fa02da0dd1f843dc011376965e0c8c6c9b5 and later · before 5bcd4d3058ebaf46ad2e163829d87dd4870c7a45affected · git
    • before 3.2not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.180-16.1.180-1
Debian:13linuxbefore 6.12.100-16.12.100-1
Debian:14linuxbefore 7.1.5-17.1.5-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-72106Aug 15, 2026 · dm-ioctl: fix a possible overflow in list_version_get_info
    0Monitor
  • ← EarlierCVE-2026-72107Aug 15, 2026 · dm era: fix out-of-bounds memory access for non-zero start sector
    35Monitor
  • Later →CVE-2026-72110Aug 15, 2026 · bpf,fork: wipe ->bpf_storage before bailouts that access it
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux3dc9ae1029320d77472c44965e572f176949cd63Vendor (CNA)
Linux Linux4af993468193cf4cd32ba5748786e7801945f7d2Vendor (CNA)
Linux Linux5bcd4d3058ebaf46ad2e163829d87dd4870c7a45Vendor (CNA)
Linux Linux5efb1a7734ed4035fa4fdc3716bdb84621f27cf6Vendor (CNA)
Linux Linux7f76245960a332f39b08cc556e675d1765dc5bbbVendor (CNA)
Linux Linux9f1a0d27586ceab055e6b050e3731ce3c6b2c4f0Vendor (CNA)
Linux Linuxabf2fae92cbe68945028987d498cc72f8f0e23a8Vendor (CNA)
Linux Linuxb5f9a31c51cbb374a1713c3494f8660ab070f035Vendor (CNA)
debian:linux6.1.180-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-672 · Operation on a Resource after Expiration or Release

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records