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CVE-2026-89686— nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke

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.

在 Linux 内核中，以下漏洞已得到修复： nfsd: 修复因委托（delegation）撤销竞态导致的 nfsd4_alloc_layout_stateid 中的 BUG_ON 在父 stateid 为委托（delegation）时，在未持有 的情况下读取 。与此同时，通过 laundromat（后台清理线程）执行的并发委托撤销操作会在持有 的情况下将 清空，导致 返回 ，从而触发 断言失败。 该竞态条件可被客户端触发：两个 NFS 客户端可通过如下方式引发此问题——其中一个客户端持有委托，另一个客户端打开同一

AI Predicted 4.7 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1210 · Exploitation of Remote Services

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux c5c707f96fc9a6e5a57ca5baac892673270abe3d< c517f27498757e616d2a8fe6d16caad1fee422e6 affected
c5c707f96fc9a6e5a57ca5baac892673270abe3d< 607a56fea772c1f4f4989d8e255dd4f7192d9604 affected
c5c707f96fc9a6e5a57ca5baac892673270abe3d< 97bda8b4284d90897a1f1922e5082ff9e35d7c7e affected
c5c707f96fc9a6e5a57ca5baac892673270abe3d< ca94ba36172046be6a694a7986f6931e47ed4d51 affected
4.0 affected
< 4.0 unaffected
6.12.109≤ 6.12.* unaffected
6.18.50≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-89686

Vulnerability Information
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Vulnerability Title
nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke nfsd4_alloc_layout_stateid reads fp->fi_deleg_file without holding fi_lock when the parent stateid is a delegation. A concurrent delegation revoke via the laundromat can clear fi_deleg_file under fi_lock, causing nfsd_file_get() to return NULL and triggering the BUG_ON. This race is client-reachable: two NFS clients can trigger it by having one hold a delegation while another opens the same file to force a recall. When the first client doesn't respond to the recall, the laundromat revokes it. A concurrent LAYOUTGET from any client using the delegation stateid hits the race window. Fix this by taking fi_lock around the fi_deleg_file read in the SC_TYPE_DELEG path, matching the locking discipline of the find_any_file() arm, and replacing the BUG_ON with a graceful error return that cleans up the partially-initialized layout stateid.
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

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux c5c707f96fc9a6e5a57ca5baac892673270abe3d ~ c517f27498757e616d2a8fe6d16caad1fee422e6 -
Linux Linux 4.0 -

II. Public POCs for CVE-2026-89686

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III. Intelligence Information for CVE-2026-89686

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Other References for CVE-2026-89686 (4)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89491 ocfs2: cluster: don't sleep while holding o2hb_live_lock in o2hb_region_pin()
CVE-2026-89477 sctp: fix NULL deref on untransmitted RECONF completion
CVE-2026-89478 sctp: drop a chunk if its transport was removed
CVE-2026-89479 sctp: stop processing a packet once its association is deleted
CVE-2026-89480 nvme-tcp: reject a read that transferred too few bytes
CVE-2026-89482 nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone
CVE-2026-89481 nvme-tcp: fix host memory disclosure on R2T for a read command
CVE-2026-89483 nvme: zero the discard fallback page
CVE-2026-89484 lockd: fix NULL dereference on lockowner allocation failure
CVE-2026-89485 lockd: pin next file across nlm_inspect_file lock-drop
CVE-2026-89486 ipmi: Fix use-after-free of cmd_rcvr in _ipmi_destroy_user()
CVE-2026-89487 openvswitch: only skb_tx_error() a packet we are about to drop
CVE-2026-89488 openvswitch: Fix CT limit teardown use-after-free
CVE-2026-89489 openrisc: fix arbitrary kernel memory access via or1k_atomic syscall
CVE-2026-89500 ring-buffer: Make cpu_buffer::free_page a buffer_data_read_page
CVE-2026-89497 orangefs: skip leading spaces before parsing client debug masks
CVE-2026-89498 orangefs: fix double-free of trailer_buf on readdir copy failure
CVE-2026-89499 ring-buffer: Stop remote reader update when page swap fails
CVE-2026-89496 ocfs2: always run deallocs on copy-on-write completion
CVE-2026-89501 ring-buffer: Hold cpu_buffer::lock when resizing a subbuf

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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