Vulnerabilities

Vulnerability · CVE-2026-72108

In the Linux kernel, the following vulnerability has been resolved: dm thin metadata: fix metadata snapshot consistency on commit failure __reserve_metadata_snap() and…

Published Aug 15, 2026 · catalog updated Oct 19, 2026 · the affected product

Open the advisory

Exploitation likelihood is not on this record for CVE-2026-72108. A missing EPSS score is not a low risk. Compare the affected product with the linked advisory before you change production.

Severity

High7.8

Known exploitation

Not in CISA/VulnCheck KEV

EPSS

Awaiting synchronization with FIRST

Remediation

Not established

Affected products

See sources for product scope

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-

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