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CVE-2026-98284— netlink: do not free nlk->groups while lockless readers can use it

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： netlink：当无锁读取器仍在使用 nlk->groups 时，不得释放它 在持有 锁的情况下使用 。每当 落在不同的 kmalloc 分桶（bucket）时，旧的位图会被立即释放。 和 的两个读取器并未持有 netlink 表锁： 1) 。从 中的 rhashtable 遍历转储（dump）已绑定（hashed）的套接字，该遍历仅持有 RCU 锁。只有转储中的 部分才持有 。 2) （位于 ），其遍历自提交 21e4902aea80（“netlink：在套接字释放中使用

AI Predicted 7.8 Difficulty: Hard EPSS 0.16% · P5

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 21e4902aea80ef35afc00ee8d2abdea4f519b7f7< 22f313e211d58a66786c81487c3905fa5d4b2a8f affected
21e4902aea80ef35afc00ee8d2abdea4f519b7f7< ceac0de741bfb47ca255eee075257b3bb31f0651 affected
4.0 affected
< 4.0 unaffected
7.2.8≤ 7.2.* unaffected
7.3-rc4≤ * unaffected
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I. Basic Information for CVE-2026-98284

Vulnerability Information
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Vulnerability Title
netlink: do not free nlk->groups while lockless readers can use it
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netlink: do not free nlk->groups while lockless readers can use it netlink_realloc_groups() uses krealloc() under netlink_table_grab(). Whenever NLGRPSZ(groups) lands in a different kmalloc bucket, the old bitmap is freed immediately. Two readers of nlk->groups / nlk->ngroups do not hold the netlink table lock: 1) sk_diag_dump_groups(). Hashed (bound) sockets are dumped from the rhashtable walk in __netlink_diag_dump(), which only holds RCU. Only the mc_list part of the dump takes nl_table_lock. 2) netlink_native_seq_show() (/proc/net/netlink), whose walk has been lockless since commit 21e4902aea80 ("netlink: Lockless lookup with RCU grace period in socket release"). Both can read a freed buffer, and sk_diag_dump_groups() can also read past the end of the old (smaller) buffer if it happens to load the old @groups pointer together with the new @ngroups value, copying the result into a NETLINK_DIAG_GROUPS attribute. This is the same class of bug that commit f773608026ee ("netlink: access nlk groups safely in netlink bind and getname") fixed for bind() and getname(); these two readers were missed. Simply grabbing the table lock in sk_diag_dump_groups() is not an option, because it is also called with nl_table_lock already held from the mc_list section of the dump. Make the lockless readers safe instead: - Allocate a new bitmap and free the old one after an RCU grace period, instead of relying on the implicit kfree() done by krealloc(). - Publish @groups before @ngroups, both with release semantics, and have the lockless readers load @ngroups first. A reader can then never pair the new (bigger) size with the old (smaller) buffer, and a reader picking up the new pointer while still seeing the old size is guaranteed to see the initialized bitmap. netlink_realloc_groups() is called from process context (bind() and setsockopt()), so kfree_rcu_mightsleep() can be used, once the table has been released.
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 21e4902aea80ef35afc00ee8d2abdea4f519b7f7 ~ 22f313e211d58a66786c81487c3905fa5d4b2a8f -
Linux Linux 4.0 -

II. Public POCs for CVE-2026-98284

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III. Intelligence Information for CVE-2026-98284

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Patches & Fixes for CVE-2026-98284 (2)

Same Patch Batch · Linux · 2026-10-06 · 208 CVEs total

CVE-2026-98323 9.8 CRITICAL RDMA/siw: Bound fragmented header copies by the remaining length
CVE-2026-98365 9.8 CRITICAL RDMA/rxe: Fix integer overflow in mr_check_range() leading to OOB access
CVE-2026-98282 8.8 HIGH powerpc/iommu: Fix the overflow validation in iommu_tce_check_ioba
CVE-2026-98283 8.8 HIGH KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()
CVE-2026-98339 8.8 HIGH wifi: cfg80211: don't filter by BSS type when removing stale entries
CVE-2026-98171 8.8 HIGH smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs
CVE-2026-98261 8.1 HIGH cifs: Fix server use-after-free in cifs_chan_skip_or_disable()
CVE-2026-98357 8.1 HIGH IB/isert: wait for deferred control PDU completions before releasing the connection
CVE-2026-98239 8.1 HIGH net: lan743x: fix RX checksum use-after-free
CVE-2026-98305 7.8 HIGH net: dsa: mxl862xx: disable the stats poll on teardown
CVE-2026-98341 7.8 HIGH wifi: cfg80211: don't free driver-owned scan requests
CVE-2026-98320 7.8 HIGH netfilter: flowtable: hold reference on ct until flow is released
CVE-2026-98228 7.8 HIGH mips: select CONFIG_WEAK_REORDERING_BEYOND_LLSC from CONFIG_EYEQ
CVE-2026-98229 7.8 HIGH xfrm: save input state data before secpath resets
CVE-2026-98318 7.8 HIGH smb: client: validate absolute native symlink targets before NT fixups
CVE-2026-98315 7.8 HIGH ntfs: protect runlist updates with the runlist lock
CVE-2026-98260 7.8 HIGH exec: Cleanup POSIX timers right after de_thread()
CVE-2026-98256 7.8 HIGH signal: Prevent exec() race
CVE-2026-98258 7.8 HIGH posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list
CVE-2026-98254 7.8 HIGH swiotlb: use the adjusted address for the highmem page lookup

Showing top 20 of 208 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98284

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