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CVE-2026-43391— nsfs: tighten permission checks for handle opening

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于nsfs权限检查不严格，可能导致特权服务泄露其他特权服务的命名空间信息。

CVSS 8.8 · High EPSS 0.17% · P6

Possible ATT&CK Techniques 1 AI

T1003 · OS Credential Dumping

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 5222470b2fbb3740f931f189db33dd1367b1ae75< 24ebaf6676ae4f74f4856eb645959b15e62bc1b4 affected
5222470b2fbb3740f931f189db33dd1367b1ae75< 1797ee11451f1b2be69863a9f5bd43b948813fdf affected
5222470b2fbb3740f931f189db33dd1367b1ae75< d2324a9317f00013facb0ba00b00440e19d2af5e affected
6.18 affected
< 6.18 unaffected
6.18.50≤ 6.18.* unaffected
6.19.9≤ 6.19.* unaffected
7.0≤ * unaffected
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I. Basic Information for CVE-2026-43391

Vulnerability Information
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Vulnerability Title
nsfs: tighten permission checks for handle opening
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nsfs: tighten permission checks for handle opening Even privileged services should not necessarily be able to see other privileged service's namespaces so they can't leak information to each other. Use may_see_all_namespaces() helper that centralizes this policy until the nstree adapts.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于nsfs权限检查不严格，可能导致特权服务泄露其他特权服务的命名空间信息。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 5222470b2fbb3740f931f189db33dd1367b1ae75 ~ 24ebaf6676ae4f74f4856eb645959b15e62bc1b4 -
Linux Linux 6.18 -

II. Public POCs for CVE-2026-43391

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III. Intelligence Information for CVE-2026-43391

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Patches & Fixes for CVE-2026-43391 (3)

Same Patch Batch · Linux · 2026-05-08 · 197 CVEs total

CVE-2026-43376 9.8 CRITICAL ksmbd: fix use-after-free by using call_rcu() for oplock_info
CVE-2026-43341 9.8 CRITICAL net/ipv6: ioam6: prevent schema length wraparound in trace fill
CVE-2026-43378 9.8 CRITICAL smb: server: fix use-after-free in smb2_open()
CVE-2026-43414 9.8 CRITICAL scsi: qla2xxx: Completely fix fcport double free
CVE-2026-43402 9.8 CRITICAL kthread: consolidate kthread exit paths to prevent use-after-free
CVE-2026-43379 9.8 CRITICAL ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
CVE-2026-43465 9.8 CRITICAL net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-43304 9.8 CRITICAL libceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-43384 9.8 CRITICAL net/tcp-ao: Fix MAC comparison to be constant-time
CVE-2026-43383 9.4 CRITICAL net/tcp-md5: Fix MAC comparison to be constant-time
CVE-2026-43407 9.1 CRITICAL libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
CVE-2026-43406 9.1 CRITICAL libceph: prevent potential out-of-bounds reads in process_message_header()
CVE-2026-43322 8.8 HIGH Bluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-43284 8.8 HIGH xfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-43291 8.3 HIGH net: nfc: nci: Fix parameter validation for packet data
CVE-2026-43365 8.2 HIGH xfs: fix undersized l_iclog_roundoff values
CVE-2026-43452 8.2 HIGH netfilter: x_tables: guard option walkers against 1-byte tail reads
CVE-2026-43466 8.2 HIGH net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery

Showing top 20 of 197 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43391

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