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CVE-2026-89677— nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file()

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 nfsd4_create_file() 中可能使用错误 dentry 进行 fh_compose 的问题 dentry_create() 在理论上可能返回与传入参数不同的 dentry。例如，当导出的文件系统是 NFS，且服务器在 OPEN 操作后返回的文件句柄恰好匹配了一个已存在于 dcache 中的目录时，就可能发生这种情况。这显然不符合预期！ 如果这种情况发生，之前已存储在 resfhp 中的 dentry（子节点）可能会被释放，随后被再次解引用，

AI Predicted 5.5 Difficulty: Theoretical

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 64a989dbd144e0622371396461b11335459692d2< 033e783709ce99662cf81f6abcad746a8da9d35f affected
64a989dbd144e0622371396461b11335459692d2< 3e2c79360c6a89975ec5b5a7d4ef937e4db91a27 affected
7.0 affected
< 7.0 unaffected
7.2.4≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
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I. Basic Information for CVE-2026-89677

Vulnerability Information
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Vulnerability Title
nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file() dentry_create() can hypothetically provide a different dentry than the one passed in. This could happen, for example, if the exported filesystem is NFS, and the server returned to OPEN a filehandle which matched a directory that was already in the dcache. Clearly this would not be expected! If this were to happen the dentry (child) that was already stored in resfhp could be freed and later dereferenced. We shouldn't call fh_compose() until we are certain that we have the final dentry, so this patch moved the fh_compose() call to two places: one for the case where the target already exists, and one after dentry_create() where it was created.
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 64a989dbd144e0622371396461b11335459692d2 ~ 033e783709ce99662cf81f6abcad746a8da9d35f -
Linux Linux 7.0 -

II. Public POCs for CVE-2026-89677

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III. Intelligence Information for CVE-2026-89677

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Patches & Fixes for CVE-2026-89677 (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-2026-89677

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