{"cve":"CVE-2026-43361","nvd":{"published":"2026-05-08T15:16:46.980","modified":"2026-06-17T10:49:27.210","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix transaction abort when snapshotting received subvolumes\n\nCurrently a user can trigger a transaction abort by snapshotting a\npreviously received snapshot a bunch of times until we reach a\nBTRFS_UUID_KEY_RECEIVED_SUBVOL item overflow (the maximum item size we\ncan store in a leaf). This is very likely not common in practice, but\nif it happens, it turns the filesystem into RO mode. The snapshot, send\nand set_received_subvol and subvol_setflags (used by receive) don't\nrequire CAP_SYS_ADMIN, just inode_owner_or_capable(). A malicious user\ncould use this to turn a filesystem into RO mode and disrupt a system.\n\nReproducer script:\n\n  $ cat test.sh\n  #!/bin/bash\n\n  DEV=/dev/sdi\n  MNT=/mnt/sdi\n\n  # Use smallest node size to make the test faster.\n  mkfs.btrfs -f --nodesize 4K $DEV\n  mount $DEV $MNT\n\n  # Create a subvolume and set it to RO so that it can be used for send.\n  btrfs subvolume create $MNT/sv\n  touch $MNT/sv/foo\n  btrfs property set $MNT/sv ro true\n\n  # Send and receive the subvolume into snaps/sv.\n  mkdir $MNT/snaps\n  btrfs send $MNT/sv | btrfs receive $MNT/snaps\n\n  # Now snapshot the received subvolume, which has a received_uuid, a\n  # lot of times to trigger the leaf overflow.\n  total=500\n  for ((i = 1; i <= $total; i++)); do\n      echo -ne \"\\rCreating snapshot $i/$total\"\n      btrfs subvolume snapshot -r $MNT/snaps/sv $MNT/snaps/sv_$i > /dev/null\n  done\n  echo\n\n  umount $MNT\n\nWhen running the test:\n\n  $ ./test.sh\n  (...)\n  Create subvolume '/mnt/sdi/sv'\n  At subvol /mnt/sdi/sv\n  At subvol sv\n  Creating snapshot 496/500ERROR: Could not create subvolume: Value too large for defined data type\n  Creating snapshot 497/500ERROR: Could not create subvolume: Read-only file system\n  Creating snapshot 498/500ERROR: Could not create subvolume: Read-only file system\n  Creating snapshot 499/500ERROR: Could not create subvolume: Read-only file system\n  Creating snapshot 500/500ERROR: Could not create subvolume: Read-only file system\n\nAnd in dmesg/syslog:\n\n  $ dmesg\n  (...)\n  [251067.627338] BTRFS warning (device sdi): insert uuid item failed -75 (0x4628b21c4ac8d898, 0x2598bee2b1515c91) type 252!\n  [251067.629212] ------------[ cut here ]------------\n  [251067.630033] BTRFS: Transaction aborted (error -75)\n  [251067.630871] WARNING: fs/btrfs/transaction.c:1907 at create_pending_snapshot.cold+0x52/0x465 [btrfs], CPU#10: btrfs/615235\n  [251067.632851] Modules linked in: btrfs dm_zero (...)\n  [251067.644071] CPU: 10 UID: 0 PID: 615235 Comm: btrfs Tainted: G        W           6.19.0-rc8-btrfs-next-225+ #1 PREEMPT(full)\n  [251067.646165] Tainted: [W]=WARN\n  [251067.646733] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014\n  [251067.648735] RIP: 0010:create_pending_snapshot.cold+0x55/0x465 [btrfs]\n  [251067.649984] Code: f0 48 0f (...)\n  [251067.653313] RSP: 0018:ffffce644908fae8 EFLAGS: 00010292\n  [251067.653987] RAX: 00000000ffffff01 RBX: ffff8e5639e63a80 RCX: 00000000ffffffd3\n  [251067.655042] RDX: ffff8e53faa76b00 RSI: 00000000ffffffb5 RDI: ffffffffc0919750\n  [251067.656077] RBP: ffffce644908fbd8 R08: 0000000000000000 R09: ffffce644908f820\n  [251067.657068] R10: ffff8e5adc1fffa8 R11: 0000000000000003 R12: ffff8e53c0431bd0\n  [251067.658050] R13: ffff8e5414593600 R14: ffff8e55efafd000 R15: 00000000ffffffb5\n  [251067.659019] FS:  00007f2a4944b3c0(0000) GS:ffff8e5b27dae000(0000) knlGS:0000000000000000\n  [251067.660115] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  [251067.660943] CR2: 00007ffc5aa57898 CR3: 00000005813a2003 CR4: 0000000000370ef0\n  [251067.661972] Call Trace:\n  [251067.662292]  <TASK>\n  [251067.662653]  create_pending_snapshots+0x97/0xc0 [btrfs]\n  [251067.663413]  btrfs_commit_transaction+0x26e/0xc00 [btrfs]\n  [251067.664257]  ? btrfs_qgroup_convert_reserved_meta+0x35/0x390 [btrfs]\n  [251067.665238]  ? _raw_spin_unlock+0x15/0x30\n  [251067.665837]  ? record_root_\n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/6bce705b699cba9afccb996c77d194fe003dfa2a","https://git.kernel.org/stable/c/770af8e465c2c3de528f85e840eab462dd41542b","https://git.kernel.org/stable/c/9a9227b488ffb7cdbb5d930a01fc6956c05ba61a","https://git.kernel.org/stable/c/bac55dde8efa457e769c934fd88a63f2141ba238","https://git.kernel.org/stable/c/e1b18b959025e6b5dbad668f391f65d34b39595a"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:33:55.586217763+00:00"},"epss":{"cve":"CVE-2026-43361","score":0.00123,"percentile":0.02024,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}