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Fencer Vulns
no cvss —

CVE-2025-68778 json

btrfs: don't log conflicting inode if it's a dir moved in the current transaction

published 2026-01-13 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-2322

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

btrfs: don't log conflicting inode if it's a dir moved in the current transaction

We can't log a conflicting inode if it's a directory and it was moved from one parent directory to another parent directory in the current transaction, as this can result an attempt to have a directory with two hard links during log replay, one for the old parent directory and another for the new parent directory.

The following scenario triggers that issue:

1) We have directories "dir1" and "dir2" created in a past transaction. Directory "dir1" has inode A as its parent directory;

2) We move "dir1" to some other directory;

3) We create a file with the name "dir1" in directory inode A;

4) We fsync the new file. This results in logging the inode of the new file and the inode for the directory "dir1" that was previously moved in the current transaction. So the log tree has the INODE_REF item for the new location of "dir1";

5) We move the new file to some other directory. This results in updating the log tree to included the new INODE_REF for the new location of the file and removes the INODE_REF for the old location. This happens during the rename when we call btrfs_log_new_name();

6) We fsync the file, and that persists the log tree changes done in the previous step (btrfs_log_new_name() only updates the log tree in memory);

7) We have a power failure;

8) Next time the fs is mounted, log replay happens and when processing the inode for directory "dir1" we find a new INODE_REF and add that link, but we don't remove the old link of the inode since we have not logged the old parent directory of the directory inode "dir1".

As a result after log replay finishes when we trigger writeback of the subvolume tree's extent buffers, the tree check will detect that we have a directory a hard link count of 2 and we get a mount failure. The errors and stack traces reported in dmesg/syslog are like this:

[ 3845.729764] BTRFS info (device dm-0): start tree-log replay [ 3845.730304] page: refcount:3 mapcount:0 mapping:000000005c8a3027 index:0x1d00 pfn:0x11510c [ 3845.731236] memcg:ffff9264c02f4e00 [ 3845.731751] aops:btree_aops [btrfs] ino:1 [ 3845.732300] flags: 0x17fffc00000400a(uptodate|private|writeback|node=0|zone=2|lastcpupid=0x1ffff) [ 3845.733346] raw: 017fffc00000400a 0000000000000000 dead000000000122 ffff9264d978aea8 [ 3845.734265] raw: 0000000000001d00 ffff92650e6d4738 00000003ffffffff ffff9264c02f4e00 [ 3845.735305] page dumped because: eb page dump [ 3845.735981] BTRFS critical (device dm-0): corrupt leaf: root=5 block=30408704 slot=6 ino=257, invalid nlink: has 2 expect no more than 1 for dir [ 3845.737786] BTRFS info (device dm-0): leaf 30408704 gen 10 total ptrs 17 free space 14881 owner 5 [ 3845.737789] BTRFS info (device dm-0): refs 4 lock_owner 0 current 30701 [ 3845.737792] item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160 [ 3845.737794] inode generation 3 transid 9 size 16 nbytes 16384 [ 3845.737795] block group 0 mode 40755 links 1 uid 0 gid 0 [ 3845.737797] rdev 0 sequence 2 flags 0x0 [ 3845.737798] atime 1764259517.0 [ 3845.737800] ctime 1764259517.572889464 [ 3845.737801] mtime 1764259517.572889464 [ 3845.737802] otime 1764259517.0 [ 3845.737803] item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12 [ 3845.737805] index 0 name_len 2 [ 3845.737807] item 2 key (256 DIR_ITEM 2363071922) itemoff 16077 itemsize 34 [ 3845.737808] location key (257 1 0) type 2 [ 3845.737810] transid 9 data_len 0 name_len 4 [ 3845.737811] item 3 key (256 DIR_ITEM 2676584006) itemoff 16043 itemsize 34 [ 3845.737813] location key (258 1 0) type 2 [ 3845.737814] transid 9 data_len 0 name_len 4 [ 3845.737815] item 4 key (256 DIR_INDEX 2) itemoff 16009 itemsize 34 [ 3845.737816] location key (257 1 0) type 2 [ ---truncated---

Patch / fix

  • Linux Linux 6.1.160, 6.6.120, 6.12.64, 6.18.3, 6.19
  • linux Debian 12 6.1.162-1
  • linux Debian 13 6.12.69-1
  • linux Debian 14 6.18.3-1

debian advisories DEBIAN-CVE-2025-68778

  • linux Ubuntu 24.04 LTS 6.8.0-110.110
  • linux Ubuntu 25.10 6.17.0-22.22
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1052.55
  • linux-aws Ubuntu 25.10 6.17.0-1012.12
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1054.57
  • linux-gcp Ubuntu 25.10 6.17.0-1012.12
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1050.56
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1051.51

ubuntu advisories UBUNTU-CVE-2025-68778

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.34.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.34.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.34.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.34.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.34.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.34.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.34.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.34.1.150700.17.23.1

suse advisories SUSE-SU-2026:1081-1SUSE-SU-2026:20845-1SUSE-SU-2026:20876-1SUSE-SU-2026:0962-1SUSE-SU-2026:20720-1SUSE-SU-2026:20667-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.26.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.26.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.26.1

opensuse advisories openSUSE-SU-2026:20287-1

  • kernel Azure Linux 3.0 6.6.121.1-1

azure linux advisories AZL-74348

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-68778 updated cvss 5.5

kernel: btrfs: don't log conflicting inode if it's a dir moved in the current transaction

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix available
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.