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CVE-2026-89659— NFSD: Prevent client use-after-free during 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：防止委托撤销过程中客户端出现“释放后使用”（use-after-free）问题 问题描述： 委托状态 ID（delegation stateid）仅持有一个指向其所属 的裸指针，而不保持该客户端对象的生命周期。客户端之所以能在其状态 ID 存活，是因为 在调用 之前会先清空 和 列表。 然而， 函数打破了这一不变量：它首先从一个过期的委托中将委托从 中解除哈希（unhash），释放 ，随后 在持有 的情况下将该委托重新链接到 列表。在这一时间窗口内，该委托既不

AI Predicted 5.5 Difficulty: Hard

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54< 3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3 affected
3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54< 2a9d637c2a8fd8ac29ad9b29f28d122ef75c1a56 affected
3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54< 4683ca76b3b7e5808338491c6eb3c20e6b4894d5 affected
3.10 affected
< 3.10 unaffected
6.18.51≤ 6.18.* unaffected
7.2.4≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
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I. Basic Information for CVE-2026-89659

Vulnerability Information
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Vulnerability Title
NFSD: Prevent client use-after-free during delegation revoke
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent client use-after-free during delegation revoke A delegation stateid holds only a bare pointer to its owning nfs4_client and does not keep it alive. The client survives its stateids only because __destroy_client() drains cl_delegations and cl_revoked before free_client() runs. nfs4_laundromat() breaks that invariant: it unhashes an expired delegation from cl_delegations, drops deleg_lock, then revoke_delegation() relinks it onto cl_revoked under cl_lock. In that window the delegation is on neither list, so client_has_state() can report no remaining state. Every teardown path first requires cl_rpc_users to be zero, but the laundromat holds no such reference. A client whose recalled delegation has just timed out can therefore reach free_client() while revoke_delegation() is still about to dereference cl_lock, a use-after-free. Pin the client with cl_rpc_users across the revoke so teardown blocks until it completes, then reap the delegation from cl_revoked. A client already expiring reaps its own, so skip it and leave the delegation on del_recall_lru.
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 3bd64a5ba1719c2bb6cba4493dfd3e23a7653e54 ~ 3c0a53ee0b442348d8d2286d6960d3f07bb3a3d3 -
Linux Linux 3.10 -

II. Public POCs for CVE-2026-89659

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III. Intelligence Information for CVE-2026-89659

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Patches & Fixes for CVE-2026-89659 (3)

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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