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CVE-2026-89662— NFSD: Prevent lock owner use-after-free during client teardown

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，已解决以下漏洞： NFSD：在客户端拆除（teardown）期间防止锁属主（lock owner）释放后使用（use-after-free）问题 会释放客户端的打开属主（open owners），但那些仅通过一个被阻塞的锁（blocked lock, 简称 nbl）保持引用的锁属主，仍然保留在 哈希表中。由于 不计入这种“裸”属主（bare owner），因此在存在此类属主的情况下， 操作可能进入 。 随后， 遍历该哈希表，对每个没有持有引用的属主调用 。当释放被阻塞的锁时，通过 字段持有的

AI Predicted 7.1 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 68ef3bc3166468678d5e1fdd216628c35bd1186f< a6ead6fff3a7d03e49845f048f7000a2e0d34431 affected
68ef3bc3166468678d5e1fdd216628c35bd1186f< 4804c58f73a80d12df1de323bf97a164f6ee8743 affected
68ef3bc3166468678d5e1fdd216628c35bd1186f< 8cf4ff0a7c083dd5e0067f517d63979b74b66649 affected
68ef3bc3166468678d5e1fdd216628c35bd1186f< 5e2fa29d223a9a1e6a948e40b109d09081d1decd affected
e294c4c2d33b7307a89cdf31bec08a112d6a9297 affected
797bfd05d4040fbf766198b3cfcc1838002cc890 affected
0f44e9da465ea259b6c9f31a627f3c50a16e1679 affected
4.9.91< 4.10 affected
… +8 more rows
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I. Basic Information for CVE-2026-89662

Vulnerability Information
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Vulnerability Title
NFSD: Prevent lock owner use-after-free during client teardown
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
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 68ef3bc3166468678d5e1fdd216628c35bd1186f ~ a6ead6fff3a7d03e49845f048f7000a2e0d34431 -
Linux Linux 4.16 -

II. Public POCs for CVE-2026-89662

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III. Intelligence Information for CVE-2026-89662

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Patches & Fixes for CVE-2026-89662 (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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