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CVE-2026-89674— nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget

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_ff_encode_layoutget 中的 XDR 长度计算 函数中的 XDR 缓冲区大小计算存在多处错误，可能导致越界写入或将未初始化的内核内存泄露给客户端： 未考虑文件句柄数据的 XDR 填充（padding）。 和 的长度计算使用了 ，但 实际写入的字节数为 。 漏算了 和 字段（共 8 字节），而 中的头部长度常量多估了 8 字节——这两者部分抵消，但仍存在净不匹配。 最坏情况出现在字符串较短时（例如 、 且文件句柄长度为奇数），

AI Predicted 6.5 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1210.003

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 9b9960a0ca4773e21c4b153ed355583946346b25< e7d9d23ecd9172f05b09bb678ff22db8e361c428 affected
9b9960a0ca4773e21c4b153ed355583946346b25< 0380129b1373c437eb35401a174671c8888f4b80 affected
9b9960a0ca4773e21c4b153ed355583946346b25< c81cef6a805dec266c10fc4f83c93d6fcf1a2b43 affected
9b9960a0ca4773e21c4b153ed355583946346b25< f9868174af49d207fbaf0c5e055d088a983684af affected
4.8 affected
< 4.8 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-2026-89674

Vulnerability Information
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Vulnerability Title
nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget The XDR buffer size calculation in nfsd4_ff_encode_layoutget() has multiple errors that can result in either an out-of-bounds write or leaking uninitialized kernel memory to the client: - fh_len doesn't account for XDR padding on the file handle data - uid and gid lengths use "8 + len" but xdr_encode_opaque() actually writes "4 + xdr_align_size(len)" bytes - ds_len omits the flags and stats_collect_hint fields (8 bytes), while len's header constant overestimates by 8 bytes -- these partially cancel but leave a net mismatch The worst case occurs with short strings (e.g. uid=0, gid=0 with an odd-sized file handle), where the function writes up to 5 bytes past the reserved XDR buffer. Conversely, when string lengths happen to be 4-byte aligned, the reservation is too large and stale buffer content is sent to the client. Fix this by breaking out every encoded field explicitly in the ds_len calculation, using xdr_align_size() for all variable-length opaque fields, and correcting the header constants.
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 9b9960a0ca4773e21c4b153ed355583946346b25 ~ e7d9d23ecd9172f05b09bb678ff22db8e361c428 -
Linux Linux 4.8 -

II. Public POCs for CVE-2026-89674

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III. Intelligence Information for CVE-2026-89674

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Other References for CVE-2026-89674 (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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