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CVE-2026-89685— nfsd: fix clock domain mismatch in clients_still_reclaiming()

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，修复了以下漏洞： nfsd：修复 clients_still_reclaiming() 中的时钟域不匹配问题 从 （基于 CLOCK_REALTIME，数值约为 17 亿）计算截止时间（deadline），但将其与 （基于 CLOCK_BOOTTIME，表示系统启动后的秒数）进行比较。由于两个时钟域不一致，该比较结果始终为假——需要系统连续运行约 54 年，CLOCK_BOOTTIME 才能超过由 CLOCK_REALTIME 推导出的截止时间。 这意味着任何客户端都可以通过发送 CLAIM

AI Predicted 7.4 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1029 · Scheduled Transfer

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 20b7d86f29d39e8ae19bb29c24ffee70dc385ddf< f9cec313efb2fd18d962aad738a4892bce806016 affected
20b7d86f29d39e8ae19bb29c24ffee70dc385ddf< 9843649196221152b6e5d138a3ce859bdaae1d96 affected
20b7d86f29d39e8ae19bb29c24ffee70dc385ddf< 09ea3eb9a518565f5bca386e81b993ed8825f5e8 affected
5.6 affected
< 5.6 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-2026-89685

Vulnerability Information
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Vulnerability Title
nfsd: fix clock domain mismatch in clients_still_reclaiming()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix clock domain mismatch in clients_still_reclaiming() clients_still_reclaiming() computes a deadline from nn->boot_time (CLOCK_REALTIME, ~1.7 billion) but compares it against ktime_get_boottime_seconds() (CLOCK_BOOTTIME, seconds since boot). The comparison is always false — it would take ~54 years of uptime for BOOTTIME to exceed the REALTIME-derived deadline. This means any client can hold the server in grace indefinitely by sending CLAIM_PREVIOUS OPEN requests, blocking all non-reclaim operations for all other clients. Add boot_time_bt (CLOCK_BOOTTIME) alongside the existing boot_time and use it for the deadline computation. boot_time (CLOCK_REALTIME) is preserved for its cl_boot clientid-nonce role.
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 20b7d86f29d39e8ae19bb29c24ffee70dc385ddf ~ f9cec313efb2fd18d962aad738a4892bce806016 -
Linux Linux 5.6 -

II. Public POCs for CVE-2026-89685

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III. Intelligence Information for CVE-2026-89685

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Patches & Fixes for CVE-2026-89685 (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

V. Comments for CVE-2026-89685

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