CVE-2026-46160 btrfs: fix missing last_unlink_trans update when removing a directory

Medium 5.5 Published 28 May 2026 Updated 19 Jun 2026

A missing update in the btrfs filesystem code can cause log replay failures and mount errors after a power loss, leading to denial of service.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-46160?

CVE-2026-46160 is a medium-severity denial of service vulnerability in Linux kernel, published on 28 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

btrfs: fix missing last_unlink_trans update when removing a directory

When removing a directory we are not updating its last_unlink_trans field, which can result in incorrect fsync behaviour in case some one fsyncs the directory after it was removed because it's holding a file descriptor on it.

Example scenario:

mkdir /mnt/dir1 mkdir /mnt/dir1/dir2 mkdir /mnt/dir3

sync -f /mnt

# Do some change to the directory and fsync it. chmod 700 /mnt/dir1 xfs_io -c fsync /mnt/dir1

# Move dir2 out of dir1 so that dir1 becomes empty. mv /mnt/dir1/dir2 /mnt/dir3/

open fd on /mnt/dir1 call rmdir(2) on path "/mnt/dir1" fsync fd

When attempting to mount the filesystem, the log replay will fail with an -EIO error and dmesg/syslog has the following:

[445771.626482] BTRFS info (device dm-0): first mount of filesystem 0368bbea-6c5e-44b5-b409-09abe496e650 [445771.626486] BTRFS info (device dm-0): using crc32c checksum algorithm [445771.627912] BTRFS info (device dm-0): start tree-log replay [445771.628335] page: refcount:2 mapcount:0 mapping:0000000061443ddc index:0x1d00 pfn:0x7072a5 [445771.629453] memcg:ffff89f400351b00 [445771.629892] aops:btree_aops [btrfs] ino:1 [445771.630737] flags: 0x17fffc00000402a(uptodate|lru|private|writeback|node=0|zone=2|lastcpupid=0x1ffff) [445771.632359] raw: 017fffc00000402a fffff47284d950c8 fffff472907b7c08 ffff89f458e412b8 [445771.633713] raw: 0000000000001d00 ffff89f6c51d1a90 00000002ffffffff ffff89f400351b00 [445771.635029] page dumped because: eb page dump [445771.635825] BTRFS critical (device dm-0): corrupt leaf: root=5 block=30408704 slot=10 ino=258, invalid nlink: has 2 expect no more than 1 for dir [445771.638088] BTRFS info (device dm-0): leaf 30408704 gen 10 total ptrs 17 free space 14878 owner 5 [445771.638091] BTRFS info (device dm-0): refs 4 lock_owner 0 current 3581087 [445771.638094] item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160 [445771.638097] inode generation 3 transid 9 size 16 nbytes 16384 [445771.638098] block group 0 mode 40755 links 1 uid 0 gid 0 [445771.638100] rdev 0 sequence 2 flags 0x0 [445771.638102] atime 1775744884.0 [445771.660056] ctime 1775744885.645502983 [445771.660058] mtime 1775744885.645502983 [445771.660060] otime 1775744884.0 [445771.660062] item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12 [445771.660064] index 0 name_len 2 [445771.660066] item 2 key (256 DIR_ITEM 1843588421) itemoff 16077 itemsize 34 [445771.660068] location key (259 1 0) type 2 [445771.660070] transid 9 data_len 0 name_len 4 [445771.660075] item 3 key (256 DIR_ITEM 2363071922) itemoff 16043 itemsize 34 [445771.660076] location key (257 1 0) type 2 [445771.660077] transid 9 data_len 0 name_len 4 [445771.660078] item 4 key (256 DIR_INDEX 2) itemoff 16009 itemsize 34 [445771.660079] location key (257 1 0) type 2 [445771.660080] transid 9 data_len 0 name_len 4 [445771.660081] item 5 key (256 DIR_INDEX 3) itemoff 15975 itemsize 34 [445771.660082] location key (259 1 0) type 2 [445771.660083] transid 9 data_len 0 name_len 4 [445771.660084] item 6 key (257 INODE_ITEM 0) itemoff 15815 itemsize 160 [445771.660086] inode generation 9 transid 9 size 8 nbytes 0 [445771.660087] block group 0 mode 40777 links 1 uid 0 gid 0 [445771.660088] rdev 0 sequence 2 flags 0x0 [445771.660089] atime 1775744885.641174097 [445771.660090] ctime 1775744885.645502983 [445771.660091] mtime 1775744885.645502983 [445771.660105] otime 1775744885.641174097 [445771.660106] item 7 key (257 INODE_REF 256) itemoff 15801 itemsize 14 [445771.660107] index 2 name_len 4 [445771.660108] item 8 key (257 DIR_ITEM 2676584006) itemoff 15767 itemsize 34 [445771.660109] location key (2 ---truncated---

Which versions are affected by CVE-2026-46160?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-46160?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-46160 being exploited?

There is no known exploitation of CVE-2026-46160 in the wild and no public exploit code.

All Linux kernel vulnerabilities

Sources

Also known as AZL-89034, BELL-CVE-2026-46160, DEBIAN-CVE-2026-46160, GHSA-xvrh-2655-9jjv, ROOT-OS-DEBIAN-11-CVE-2026-46160, ROOT-OS-DEBIAN-12-CVE-2026-46160 and 4 more.