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

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-89661— NFSD: Prevent post-shutdown use-after-free in unlock_filesystem

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：防止 unlock_filesystem 中的释放后使用（use-after-free）漏洞 向 写入一个文件系统路径时，会在持有 之前以及确认 已设置之前，调用 。一旦 NFSD 服务关闭， 已释放了 ，但指针本身未被置空。因此，该取消辅助函数会将已释放的 slab 内存当作 数组进行遍历，并在尝试获取 时解引用了一个无效的 指针。持有 权限的本地管理员可以通过先停止服务器，然后向 写入来触发此“释放后使用”漏洞；KASAN 报告在 中发生 slab 内存释

AI Predicted 5.5 Difficulty: Moderate

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 3daab3112f039cf849f96764019b096bb0a39d04< 0c1a755b7212e0835398d4df5e782ea85ccd7476 affected
3daab3112f039cf849f96764019b096bb0a39d04< 292d915d3ba6fd15eeb88351fa10581683073109 affected
7.0 affected
< 7.0 unaffected
7.2.4≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-89661

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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.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
NFSD: Prevent post-shutdown use-after-free in unlock_filesystem
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent post-shutdown use-after-free in unlock_filesystem Writing a filesystem path to /proc/fs/nfsd/unlock_filesystem runs nfsd4_cancel_copy_by_sb() before nfsd_mutex is held and before the handler confirms that nn->nfsd_serv is set. Once nfsd has shut down, nfs4_state_destroy_net() has freed nn->conf_id_hashtbl but left the pointer intact, so the cancel helper iterates freed slab memory as an array of struct list_head and then dereferences a bogus nfs4_client when it takes clp->async_lock. A local administrator holding CAP_SYS_ADMIN can reach this use-after-free by stopping the server and then writing to unlock_filesystem; KASAN reports a slab-use-after-free read in nfsd4_cancel_copy_by_sb(). nfsd4_revoke_states() walks the same state tables and for that reason already runs only under nfsd_mutex with nn->nfsd_serv confirmed present. Move the async COPY cancel into that protected section so every NFSv4 state-table walker on this path observes a running server. Async copies exist only while the server runs, so gating the cancel on nn->nfsd_serv loses nothing.
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 3daab3112f039cf849f96764019b096bb0a39d04 ~ 0c1a755b7212e0835398d4df5e782ea85ccd7476 -
Linux Linux 7.0 -

II. Public POCs for CVE-2026-89661

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

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-89661

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-89661 (2)

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

V. Comments for CVE-2026-89661

No comments yet

Leave a comment