Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-23249— xfs: check for deleted cursors when revalidating two btrees

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于xrep_revalidate_allocbt函数中未检查已删除的游标，可能导致空指针取消引用。

AI Predicted 6.5 Difficulty: Moderate EPSS 0.15% · P3

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux dbfbf3bdf639a20da7d5fb390cd2e197d25aa418< d69de525bc7ab27713342080bf50826df3f6a68f affected
dbfbf3bdf639a20da7d5fb390cd2e197d25aa418< b04baa848c0543b240b1bd8aecff470382f6f154 affected
dbfbf3bdf639a20da7d5fb390cd2e197d25aa418< 5991e96f2ae82df60a3e4ed00f3432d9f3502a99 affected
dbfbf3bdf639a20da7d5fb390cd2e197d25aa418< 55e03b8cbe2783ec9acfb88e8adb946ed504e117 affected
6.8 affected
< 6.8 unaffected
6.12.75≤ 6.12.* unaffected
6.18.16≤ 6.18.* unaffected
… +2 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-23249

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
xfs: check for deleted cursors when revalidating two btrees
Source: CVE Program / CVE List V5
Vulnerability Description
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 revalidate the cntbt. Therefore, check for a null cntbt cursor before that revalidation, and mark the repair incomplete. Also we can ignore the second tree entirely if the first tree was rebuilt but is already corrupt. Apply the same fix to xrep_revalidate_iallocbt because it has the same problem.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于xrep_revalidate_allocbt函数中未检查已删除的游标，可能导致空指针取消引用。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux dbfbf3bdf639a20da7d5fb390cd2e197d25aa418 ~ d69de525bc7ab27713342080bf50826df3f6a68f -
Linux Linux 6.8 -

II. Public POCs for CVE-2026-23249

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-23249

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-23249 (4)

Same Patch Batch · Linux · 2026-03-18 · 35 CVEs total

CVE-2026-23246 8.8 HIGH wifi: mac80211: bounds-check link_id in ieee80211_ml_reconfiguration
CVE-2026-23268 7.8 HIGH apparmor: fix unprivileged local user can do privileged policy management
CVE-2026-23270 7.8 HIGH net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks
CVE-2026-23253 7.8 HIGH media: dvb-core: fix wrong reinitialization of ringbuffer on reopen
CVE-2026-23243 7.8 HIGH RDMA/umad: Reject negative data_len in ib_umad_write
CVE-2026-23245 7.8 HIGH net/sched: act_gate: snapshot parameters with RCU on replace
CVE-2026-23248 7.8 HIGH perf/core: Fix refcount bug and potential UAF in perf_mmap
CVE-2025-71269 7.5 HIGH btrfs: do not free data reservation in fallback from inline due to -ENOSPC
CVE-2025-71268 7.5 HIGH btrfs: fix reservation leak in some error paths when inserting inline extent
CVE-2026-23242 7.5 HIGH RDMA/siw: Fix potential NULL pointer dereference in header processing
CVE-2026-23269 7.1 HIGH apparmor: validate DFA start states are in bounds in unpack_pdb
CVE-2026-23247 tcp: secure_seq: add back ports to TS offset
CVE-2026-23244 nvme: fix memory allocation in nvme_pr_read_keys()
CVE-2026-23250 xfs: check return value of xchk_scrub_create_subord
CVE-2026-23251 xfs: only call xf{array,blob}_destroy if we have a valid pointer
CVE-2026-23252 xfs: get rid of the xchk_xfile_*_descr calls
CVE-2025-71267 fs: ntfs3: fix infinite loop triggered by zero-sized ATTR_LIST
CVE-2025-71266 fs: ntfs3: check return value of indx_find to avoid infinite loop
CVE-2025-71265 fs: ntfs3: fix infinite loop in attr_load_runs_range on inconsistent metadata
CVE-2025-71270 LoongArch: Enable exception fixup for specific ADE subcode

Showing top 20 of 35 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23249

No comments yet

Leave a comment