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CVE-2026-89691— nfsd: clear opcnt on compound arg release to prevent OOB read

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：在释放复合参数时清零 opcnt，以防止越界读取 在释放动态分配的 ops 缓冲区后，会将 重置为内联的 数组，但保留了 的原始值（对于 NFSv4.1 及以上的复合操作，该值最大可达 200）。 如果 卡在奇数值（这可能发生在 在将其设置为奇数后进入错误处理路径的情况下），RPC 状态 dumpit 处理器会从 读取 个条目。由于 只有 8 个元素，且是 结构体中的最后一个字段，因此读取索引 8-15 会访问相邻的 slab 内存，并通过 netlink 将

AI Predicted 3.5 Difficulty: Moderate

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux bd9d6a3efa9709e653aafbeb859289feccb8e70c< 58bcdfb2b2e412088839ae740b1a95154dc0b8d0 affected
bd9d6a3efa9709e653aafbeb859289feccb8e70c< e879148867bd4c4cac42e063ffaffa187dddc6fe affected
bd9d6a3efa9709e653aafbeb859289feccb8e70c< c1a4f7b1848f95302df598217e1c7a1410c2d0c5 affected
bd9d6a3efa9709e653aafbeb859289feccb8e70c< ae4c38555e81563b8dc5eae55ffd70f0ea97aa5a affected
6.7 affected
< 6.7 unaffected
6.12.109≤ 6.12.* unaffected
6.18.50≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-89691

Vulnerability Information
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Vulnerability Title
nfsd: clear opcnt on compound arg release to prevent OOB read
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: clear opcnt on compound arg release to prevent OOB read nfsd4_release_compoundargs() resets args->ops to the inline iops[8] array when the dynamically-allocated ops buffer is freed, but leaves args->opcnt at its original value (which can be up to 200 for NFSv4.1+ compounds). If rq_status_counter is stuck at an odd value (which can happen when nfsd_dispatch() hits an error path after setting it odd), the RPC status dumpit handler reads min(opcnt, 16) entries from args->ops[]. Since iops only has 8 elements and is the last field in struct nfsd4_compoundargs, reading indices 8-15 accesses adjacent slab memory and leaks it to userspace via netlink. Zero opcnt unconditionally in nfsd4_release_compoundargs() so stale compound metadata is never exposed through the status interface. [ cel: Remove the kvfree_rcu_mightsleep() sleep from the exposure window ]
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 bd9d6a3efa9709e653aafbeb859289feccb8e70c ~ 58bcdfb2b2e412088839ae740b1a95154dc0b8d0 -
Linux Linux 6.7 -

II. Public POCs for CVE-2026-89691

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III. Intelligence Information for CVE-2026-89691

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Patches & Fixes for CVE-2026-89691 (4)

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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