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CVE-2026-89692— nfsd: clear CALLBACK_RUNNING on failed delegation recall queue

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，已修复以下漏洞： nfsd：在委托回忆队列失败时清除 CALLBACK_RUNNING 标志 在入口处通过 设置 ，以串行化回忆（recall）操作，然后调用 将回忆请求加入队列。当入队失败时，引用计数的增加会被撤销，但 标志位仍保持置位状态。唯一能够清除该标志位的位置是 （位于 ），该函数从工作队列中运行，因此在没有成功入队的情况下是无法被触发的。 这导致该标志位成为 上的永久锁存器：此后对同一委托（delegation）的任何 调用都会命中 中的早期返回保护逻辑，从而静默地跳过回忆操作。

AI Predicted 5.5 Difficulty: Hard

Possible ATT&CK Techniques 1 AI

T1690 · Prevent Command History Logging

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 1054e8ffc5c492f341bdf1888b882f1d163dd3d8< b137930ee52e3ef38915a3511d4c070463b63a32 affected
1054e8ffc5c492f341bdf1888b882f1d163dd3d8< cb2d0c4d1b3d301d042ed61365eaa8cb0141a254 affected
1054e8ffc5c492f341bdf1888b882f1d163dd3d8< b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96 affected
6.15 affected
< 6.15 unaffected
6.18.50≤ 6.18.* unaffected
7.2.4≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
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I. Basic Information for CVE-2026-89692

Vulnerability Information
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Vulnerability Title
nfsd: clear CALLBACK_RUNNING on failed delegation recall queue
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: clear CALLBACK_RUNNING on failed delegation recall queue nfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit at entry to serialize recall work, then calls nfsd4_run_cb() to queue the recall. When the queue attempt fails the refcount bump is undone, but the RUNNING bit is left set. The only site that clears the bit is nfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the workqueue and is therefore unreachable when nothing was queued. The bit becomes a permanent latch on dp->dl_recall.cb_flags: every subsequent break_lease() on the same delegation hits the early-return guard in nfsd_break_one_deleg() and silently skips the recall, so the delegation is never broken and the conflicting open or lock stalls. Fix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside the refcount_dec.
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 1054e8ffc5c492f341bdf1888b882f1d163dd3d8 ~ b137930ee52e3ef38915a3511d4c070463b63a32 -
Linux Linux 6.15 -

II. Public POCs for CVE-2026-89692

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III. Intelligence Information for CVE-2026-89692

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Patches & Fixes for CVE-2026-89692 (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-2026-89692

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