cbcvebase.
CVE-2025-37856
published 2025-05-09

CVE-2025-37856: In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these…

PriorityP419medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.26%
17.9th percentile
In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.

Affected

41 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.12.25-1 (forky)linux 6.12.25-1 (forky)
linuxlinux
linuxlinux
linuxlinux
linuxlinux
linuxlinux>= 5.15.128 < 5.165.16
linuxlinux>= 6.1.47 < 6.26.2
linuxlinux>= 6.4.12 < 6.56.5
linuxlinux>= a9f189716cf15913c453299d72f69c51a9b0f86b < bf089c4d1141b27332c092b1dcca5022c415a3b6bf089c4d1141b27332c092b1dcca5022c415a3b6
linuxlinux>= a9f189716cf15913c453299d72f69c51a9b0f86b < 909e60fb469d4101c6b08cf6e622efb062bb24a1909e60fb469d4101c6b08cf6e622efb062bb24a1
linuxlinux>= a9f189716cf15913c453299d72f69c51a9b0f86b < 185fd73e5ac06027c4be9a129e59193f6a3ef202185fd73e5ac06027c4be9a129e59193f6a3ef202
linuxlinux>= a9f189716cf15913c453299d72f69c51a9b0f86b < 7511e29cf1355b2c47d0effb39e463119913e2f67511e29cf1355b2c47d0effb39e463119913e2f6
linuxlinux_kernel< 6.12.246.12.24
linuxlinux_kernel>= 0 < 6.12.25-16.12.25-1
linuxlinux_kernel>= 0 < 6.12.25-16.12.25-1
linuxlinux_kernel>= 0 < 6.8.0-100.1006.8.0-100.100
linuxlinux_kernel>= 0 < 6.14.0-22.226.14.0-22.22
linuxlinux_kernel>= 6.13 < 6.13.126.13.12
linuxlinux_kernel>= 6.14 < 6.14.36.14.3
msrcazl3_kernel_6.6.104.2-4_on_azure_linux_3.0
msrcazl3_kernel_6.6.112.1-2_on_azure_linux_3.0
msrcazl3_kernel_6.6.117.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-3_on_azure_linux_3.0
msrcazl3_kernel_6.6.121.1-1_on_azure_linux_3.0

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
vendor_ubuntu3.2LOW
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.