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CVE-2026-97971— nstree: check listing permission before taking a namespace reference

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，已解决以下漏洞： nstree：在获取命名空间引用之前检查列举权限 函数在 尚未确定调用者是否有权查看该命名空间之前，就提前获取了候选命名空间的引用计数。而在拒绝访问的路径上， 清理操作可能会减少挂载命名空间引用计数至零，而此时我们仍然持有 RCU 读锁。由于 在此处可能引发睡眠，从而导致问题。这与 commit 2ec2aff3c8e2（“ns: ensure references are dropped outside of RCU lock”，即“命名空间：确保引用计数释放发生在 RC

CVSS 7.8 · High EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1528 · Steal Application Access Token

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux 76b6f5dfb3fda76fce1f9990d6fa58adc711122b< 9e673bf5d88aa898e52cef5c87058c3fa845bc71 affected
76b6f5dfb3fda76fce1f9990d6fa58adc711122b< 56ea4e86832d8abe8930394473566c194d189f85 affected
6.19 affected
< 6.19 unaffected
7.2.7≤ 7.2.* unaffected
7.3-rc3≤ * unaffected
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I. Basic Information for CVE-2026-97971

Vulnerability Information
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Vulnerability Title
nstree: check listing permission before taking a namespace reference
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nstree: check listing permission before taking a namespace reference legitimize_ns() takes a reference on the candidate namespace before may_list_ns() has decided whether the caller may see it. The __free(ns_put) cleanup on the denied path can drop the last reference to a mount namespace while we still hold the rcu read lock, and put_mnt_ns() may sleep there. This is the same problem commit 2ec2aff3c8e2 ("ns: make sure reference are dropped outside of rcu lock") fixed for the put_user() path. Neither ns_requested() nor may_list_ns() needs a reference, both only look at the namespace type and at the caller's own namespaces, so do the checks first and take the reference last. Splat: Voluntary context switch within RCU read-side critical section! WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x238/0x2a0, CPU#5: a/3442 CPU: 5 UID: 1000 PID: 3442 Comm: a Not tainted 7.0.0-30-generic #30-Ubuntu PREEMPT(lazy) RIP: 0010:rcu_note_context_switch+0x238/0x2a0 Call Trace: <TASK> __schedule+0xcf/0x650 schedule+0x27/0x90 schedule_preempt_disabled+0x15/0x30 __mutex_lock.constprop.0+0x550/0xaf0 __mutex_lock_slowpath+0x13/0x20 mutex_lock+0x3b/0x50 exp_funnel_lock+0xb2/0x260 synchronize_rcu_expedited+0xe7/0x220 namespace_unlock+0x26a/0x320 put_mnt_ns+0xd3/0x120 mntns_put+0xe/0x20 do_listns+0x13e/0x560 __do_sys_listns+0x126/0x2d0 __x64_sys_listns+0x20/0x30 x64_sys_call+0x2366/0x2390 do_syscall_64+0x105/0x5a0 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK>
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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 76b6f5dfb3fda76fce1f9990d6fa58adc711122b ~ 9e673bf5d88aa898e52cef5c87058c3fa845bc71 -
Linux Linux 6.19 -

II. Public POCs for CVE-2026-97971

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III. Intelligence Information for CVE-2026-97971

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Patches & Fixes for CVE-2026-97971 (2)

Same Patch Batch · Linux · 2026-09-25 · 372 CVEs total

CVE-2026-100075 9.8 CRITICAL RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters
CVE-2026-97555 8.8 HIGH smb: client: fix heap overflow in DACL owner/group rewrite
CVE-2026-97957 8.8 HIGH net: hinic: fix mailbox segment buffer overflow
CVE-2026-97527 8.8 HIGH scsi: qla2xxx: Serialize NVMe unsol ctx list with a per-fcport lock
CVE-2026-97528 8.8 HIGH scsi: qla2xxx: Unlink NVMe unsol ctx before freeing on LS reject error
CVE-2026-98115 8.8 HIGH ksmbd: safely drain sessions during logoff
CVE-2026-97525 8.2 HIGH x86/mm/pat: Allocate split page tables as kernel page tables
CVE-2026-98069 8.1 HIGH net/rds: acquire the fastpath locks in rds_conn_shutdown()
CVE-2026-97573 8.1 HIGH bnxt_en: Handle buffer allocation failure in bnxt_rx_ring_reset()
CVE-2026-97570 8.1 HIGH bnxt_en: Bound SW TPA IDs to prevent crashes
CVE-2026-98130 8.1 HIGH sctp: fix a TOCTOU race in SCTP_CMD_TIMER_START
CVE-2026-98070 8.1 HIGH net/rds: acquire RDS_IN_XMIT in rds_tcp_reset_callbacks()
CVE-2026-97941 7.8 HIGH mm/slab: take n->list_lock in __slab_try_return_freelist() to avoid race
CVE-2026-97575 7.8 HIGH media: v4l2-ctrls: validate AV1 tile counts
CVE-2026-97576 7.8 HIGH media: v4l2-ctrls: validate HEVC tile counts
CVE-2026-98002 7.8 HIGH iommu/amd: Fix ineffective error check in nested domain allocation
CVE-2026-98112 7.8 HIGH ksmbd: fix listener task lifetime on netdev events
CVE-2026-97937 7.8 HIGH ftrace: fork: Initialize function graph state before copy_exec_state()
CVE-2026-97580 7.8 HIGH media: rkvdec: bound HEVC tile loops and PPS id to the array capacity
CVE-2026-97940 7.8 HIGH ipv6: fix fib6 walker UAF on seq stop

Showing top 20 of 372 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

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Same vendor: Linux

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