{"id":"CVE-2026-43299","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs fl…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs fl…","severity":"medium","cvss":5.5,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.13, < 6.19.6"],"patched":["linux_kernel 6.19.6"],"published":"2026-05-08","updated":"2026-10-15","sourceUpdated":"2026-10-15T11:17:30.560","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-43299","references":[{"url":"https://git.kernel.org/stable/c/81e1ae665004b99a10686473d99f0a7cb6335f38","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8ceaad6cd6e7fa5f73b0b2796a2e85d75d37e9f3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f6df18c001e3dcebc08482d0adeacd0cfea08593","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd","cve.org"],"epss":0.00117,"epssPercentile":0.01576,"ingestedAt":"2026-10-15T11:00:41.711Z","slug":"CVE-2026-43299","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not ASSERT() when the fs flips RO inside btrfs_repair_io_failure()\n\n[BUG]\nThere is a bug report that when btrfs hits ENOSPC error in a critical\npath, btrfs flips RO (this part is expected, although the ENOSPC bug\nstill needs to be addressed).\n\nThe problem is after the RO flip, if there is a read repair pending, we\ncan hit the ASSERT() inside btrfs_repair_io_failure() like the following:\n\n  BTRFS info (device vdc): relocating block group 30408704 flags metadata|raid1\n  ------------[ cut here ]------------\n  BTRFS: Transaction aborted (error -28)\n  WARNING: fs/btrfs/extent-tree.c:3235 at __btrfs_free_extent.isra.0+0x453/0xfd0, CPU#1: btrfs/383844\n  Modules linked in: kvm_intel kvm irqbypass\n  [...]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device vdc state EA): 2 enospc errors during balance\n  BTRFS info (device vdc state EA): balance: ended with status: -30\n  BTRFS error (device vdc state EA): parent transid verify failed on logical 30556160 mirror 2 wanted 8 found 6\n  BTRFS error (device vdc state EA): bdev /dev/nvme0n1 errs: wr 0, rd 0, flush 0, corrupt 10, gen 0\n  [...]\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  ------------[ cut here ]------------\n  assertion failed: !(fs_info->sb->s_flags & SB_RDONLY) :: 0, in fs/btrfs/bio.c:938\n  kernel BUG at fs/btrfs/bio.c:938!\n  Oops: invalid opcode: 0000 [#1] SMP NOPTI\n  CPU: 0 UID: 0 PID: 868 Comm: kworker/u8:13 Tainted: G        W        N  6.19.0-rc6+ #4788 PREEMPT(full)\n  Tainted: [W]=WARN, [N]=TEST\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014\n  Workqueue: btrfs-endio simple_end_io_work\n  RIP: 0010:btrfs_repair_io_failure.cold+0xb2/0x120\n  RSP: 0000:ffffc90001d2bcf0 EFLAGS: 00010246\n  RAX: 0000000000000051 RBX: 0000000000001000 RCX: 0000000000000000\n  RDX: 0000000000000000 RSI: ffffffff8305cf42 RDI: 00000000ffffffff\n  RBP: 0000000000000002 R08: 00000000fffeffff R09: ffffffff837fa988\n  R10: ffffffff8327a9e0 R11: 6f69747265737361 R12: ffff88813018d310\n  R13: ffff888168b8a000 R14: ffffc90001d2bd90 R15: ffff88810a169000\n  FS:  0000000000000000(0000) GS:ffff8885e752c000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  ------------[ cut here ]------------\n\n[CAUSE]\nThe cause of -ENOSPC error during the test case btrfs/124 is still\nunknown, although it's known that we still have cases where metadata can\nbe over-committed but can not be fulfilled correctly, thus if we hit\nsuch ENOSPC error inside a critical path, we have no choice but abort\nthe current transaction.\n\nThis will mark the fs read-only.\n\nThe problem is inside the btrfs_repair_io_failure() path that we require\nthe fs not to be mount read-only. This is normally fine, but if we are\ndoing a read-repair meanwhile the fs flips RO due to a critical error,\nwe can enter btrfs_repair_io_failure() with super block set to\nread-only, thus triggering the above crash.\n\n[FIX]\nJust replace the ASSERT() with a proper return if the fs is already\nread-only.\n\n## Affected\n\n- `linux_kernel >= 3.13, < 6.19.6`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.19.6`","depth":"sunlit","depthScore":30,"depthScoreParts":{"impact":30.3,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[{"seq":222276,"id":"CVE-2026-43299","ts":1792065864756,"field":"cvss","old":null,"new":"5.5"},{"seq":222275,"id":"CVE-2026-43299","ts":1792065864756,"field":"severity","old":"none","new":"medium"}]}