cbcvebase.
CVE-2026-23157
published 2026-02-14

CVE-2026-23157: In the Linux kernel, the following vulnerability has been resolved: btrfs: do not strictly require dirty metadata threshold for metadata writepages [BUG] There…

PriorityP423medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.13%
2.6th percentile
In the Linux kernel, the following vulnerability has been resolved: btrfs: do not strictly require dirty metadata threshold for metadata writepages [BUG] There is an internal report that over 1000 processes are waiting at the io_schedule_timeout() of balance_dirty_pages(), causing a system hang and trigger a kernel coredump. The kernel is v6.4 kernel based, but the root problem still applies to any upstream kernel before v6.18. [CAUSE] From Jan Kara for his wisdom on the dirty page balance behavior first. This cgroup dirty limit was what was actually playing the role here because the cgroup had only a small amount of memory and so the dirty limit for it was something like 16MB. Dirty throttling is responsible for enforcing that nobody can dirty (significantly) more dirty memory than there's dirty limit. Thus when a task is dirtying pages it periodically enters into balance_dirty_pages() and we let it sleep there to slow down the dirtying. When the system is over dirty limit already (either globally or within a cgroup of the running task), we will not let the task exit from balance_dirty_pages() until the number of dirty pages drops below the limit. So in this particular case, as I already mentioned, there was a cgroup with relatively small amount of memory and as a result with dirty limit set at 16MB. A task from that cgroup has dirtied about 28MB worth of pages in btrfs btree inode and these were practically the only dirty pages in that cgroup. So that means the only way to reduce the dirty pages of that cgroup is to writeback the dirty pages of btrfs btree inode, and only after that those processes can exit balance_dirty_pages(). Now back to the btrfs part, btree_writepages() is responsible for writing back dirty btree inode pages. The problem here is, there is a btrfs internal threshold that if the btree inode's dirty bytes are below the 32M threshold, it will not do any writeback. This behavior is to batch as much metadata as possible so we won't wri

Affected

56 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.18.9-1 (forky)linux 6.18.9-1 (forky)
linuxlinux
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < 6a8b6242eaa1dd7a0de2d6de6420d10ffe68db906a8b6242eaa1dd7a0de2d6de6420d10ffe68db90
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < bb9be3f713652e330df00f3724c18c7a5469e7acbb9be3f713652e330df00f3724c18c7a5469e7ac
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < 4357e02cafabe01c2d737ceb4c4c6382fc2ee10a4357e02cafabe01c2d737ceb4c4c6382fc2ee10a
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < 0c3666ec188640c20e254011e7adf4464c32ee580c3666ec188640c20e254011e7adf4464c32ee58
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < 629666d20c7dcd740e193ec0631fdff035b1f7d6629666d20c7dcd740e193ec0631fdff035b1f7d6
linuxlinux>= 793955bca66c99defdffc857ae6eb7e8431d6bbe < 4e159150a9a56d66d247f4b5510bed46fe58aa1c4e159150a9a56d66d247f4b5510bed46fe58aa1c
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.18.9-16.18.9-1
linuxlinux_kernel>= 2.6.29 < 6.18.96.18.9
msrccbl2_kernel_5.15.200.1-1_on_cbl_mariner_2.0
msrccbl2_kernel_5.15.202.1-1_on_cbl_mariner_2.0
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-5.15
ubuntulinux-aws-fips
ubuntulinux-azure
ubuntulinux-azure-5.15
ubuntulinux-azure-6.17
ubuntulinux-azure-6.8
ubuntulinux-azure-fde
ubuntulinux-azure-fde-5.15
ubuntulinux-azure-fde-6.17
ubuntulinux-azure-fde-6.8

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_ubuntu7.1HIGH
vendor_debian5.5MEDIUM
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
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