cbcvebase.
CVE-2026-23249
published 2026-03-18

CVE-2026-23249: In the Linux kernel, the following vulnerability has been resolved: xfs: check for deleted cursors when revalidating two btrees The free space and inode btree…

PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.14%
3.9th percentile
In the Linux kernel, the following vulnerability has been resolved: xfs: check for deleted cursors when revalidating two btrees The free space and inode btree repair functions will rebuild both btrees at the same time, after which it needs to evaluate both btrees to confirm that the corruptions are gone. However, Jiaming Zhang ran syzbot and produced a crash in the second xchk_allocbt call. His root-cause analysis is as follows (with minor corrections): In xrep_revalidate_allocbt(), xchk_allocbt() is called twice (first for BNOBT, second for CNTBT). The cause of this issue is that the first call nullified the cursor required by the second call. Let's first enter xrep_revalidate_allocbt() via following call chain: xfs_file_ioctl() -> xfs_ioc_scrubv_metadata() -> xfs_scrub_metadata() -> `sc->ops->repair_eval(sc)` -> xrep_revalidate_allocbt() xchk_allocbt() is called twice in this function. In the first call: /* Note that sc->sm->sm_type is XFS_SCRUB_TYPE_BNOPT now */ xchk_allocbt() -> xchk_btree() -> `bs->scrub_rec(bs, recp)` -> xchk_allocbt_rec() -> xchk_allocbt_xref() -> xchk_allocbt_xref_other() since sm_type is XFS_SCRUB_TYPE_BNOBT, pur is set to &sc->sa.cnt_cur. Kernel called xfs_alloc_get_rec() and returned -EFSCORRUPTED. Call chain: xfs_alloc_get_rec() -> xfs_btree_get_rec() -> xfs_btree_check_block() -> (XFS_IS_CORRUPT || XFS_TEST_ERROR), the former is false and the latter is true, return -EFSCORRUPTED. This should be caused by ioctl$XFS_IOC_ERROR_INJECTION I guess. Back to xchk_allocbt_xref_other(), after receiving -EFSCORRUPTED from xfs_alloc_get_rec(), kernel called xchk_should_check_xref(). In this function, *curpp (points to sc->sa.cnt_cur) is nullified. Back to xrep_revalidate_allocbt(), since sc->sa.cnt_cur has been nullified, it then triggered null-ptr-deref via xchk_allocbt() (second call) -> xchk_btree(). So. The bnobt revalidation failed on a cross-reference attempt, so we deleted the cntbt cursor, and then crashed when we tried to reva

Affected

44 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.19.6-1 (forky)linux 6.19.6-1 (forky)
linuxlinux
linuxlinux>= dbfbf3bdf639a20da7d5fb390cd2e197d25aa418 < d69de525bc7ab27713342080bf50826df3f6a68fd69de525bc7ab27713342080bf50826df3f6a68f
linuxlinux>= dbfbf3bdf639a20da7d5fb390cd2e197d25aa418 < b04baa848c0543b240b1bd8aecff470382f6f154b04baa848c0543b240b1bd8aecff470382f6f154
linuxlinux>= dbfbf3bdf639a20da7d5fb390cd2e197d25aa418 < 5991e96f2ae82df60a3e4ed00f3432d9f3502a995991e96f2ae82df60a3e4ed00f3432d9f3502a99
linuxlinux>= dbfbf3bdf639a20da7d5fb390cd2e197d25aa418 < 55e03b8cbe2783ec9acfb88e8adb946ed504e11755e03b8cbe2783ec9acfb88e8adb946ed504e117
linuxlinux_kernel>= 0 < 6.19.6-16.19.6-1
linuxlinux_kernel>= 6.13 < 6.18.166.18.16
linuxlinux_kernel>= 6.13.0 < 6.18.166.18.16
linuxlinux_kernel>= 6.19 < 6.19.66.19.6
linuxlinux_kernel>= 6.19.0 < 6.19.66.19.6
linuxlinux_kernel>= 6.8 < 6.12.756.12.75
linuxlinux_kernel>= 6.8.0 < 6.12.756.12.75
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-6.8
ubuntulinux-aws-fips
ubuntulinux-azure
ubuntulinux-azure-6.8
ubuntulinux-azure-fde
ubuntulinux-azure-fde-6.8
ubuntulinux-azure-fips
ubuntulinux-fips
ubuntulinux-gcp
ubuntulinux-gcp-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
vendor_ubuntu8.8HIGH
vendor_redhat5.5MEDIUM
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.