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CVE-2026-43472— unshare: fix unshare_fs() handling

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unshare组件中unshare_fs函数在CLONE_NEWNS和CLONE_NEWCGROUP组合时处理不当，可能导致挂载树状态不一致。

AI Predicted 5.5 Difficulty: Theoretical EPSS 0.11% · P1

Possible ATT&CK Techniques 1 AI

T1564.008 · Email Hiding Rules

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 741a295130606143edbf9fc740f633dbc1e6225f< 845bf3c6963a52096d0d3866e4a92db77a0c03d8 affected
741a295130606143edbf9fc740f633dbc1e6225f< d3ffc8f13034af895531a02c30b1fe3a34b46432 affected
741a295130606143edbf9fc740f633dbc1e6225f< d0d99f60538ddb4a62ccaac2168d8f448965f083 affected
741a295130606143edbf9fc740f633dbc1e6225f< d7963d6997fea86a6def242ac36198b86655f912 affected
741a295130606143edbf9fc740f633dbc1e6225f< aa9ebc084505fb26dd90f4d7a249045aad152043 affected
741a295130606143edbf9fc740f633dbc1e6225f< af8f4be3b68ac8caa41c8e5ead0eeaf5e85e42d0 affected
741a295130606143edbf9fc740f633dbc1e6225f< 42e21e74061b0ebbd859839f81acf10efad02a27 affected
741a295130606143edbf9fc740f633dbc1e6225f< 6c4b2243cb6c0755159bd567130d5e12e7b10d9f affected
… +10 more rows
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I. Basic Information for CVE-2026-43472

Vulnerability Information
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Vulnerability Title
unshare: fix unshare_fs() handling
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: unshare: fix unshare_fs() handling There's an unpleasant corner case in unshare(2), when we have a CLONE_NEWNS in flags and current->fs hadn't been shared at all; in that case copy_mnt_ns() gets passed current->fs instead of a private copy, which causes interesting warts in proof of correctness] > I guess if private means fs->users == 1, the condition could still be true. Unfortunately, it's worse than just a convoluted proof of correctness. Consider the case when we have CLONE_NEWCGROUP in addition to CLONE_NEWNS (and current->fs->users == 1). We pass current->fs to copy_mnt_ns(), all right. Suppose it succeeds and flips current->fs->{pwd,root} to corresponding locations in the new namespace. Now we proceed to copy_cgroup_ns(), which fails (e.g. with -ENOMEM). We call put_mnt_ns() on the namespace created by copy_mnt_ns(), it's destroyed and its mount tree is dissolved, but... current->fs->root and current->fs->pwd are both left pointing to now detached mounts. They are pinning those, so it's not a UAF, but it leaves the calling process with unshare(2) failing with -ENOMEM _and_ leaving it with pwd and root on detached isolated mounts. The last part is clearly a bug. There is other fun related to that mess (races with pivot_root(), including the one between pivot_root() and fork(), of all things), but this one is easy to isolate and fix - treat CLONE_NEWNS as "allocate a new fs_struct even if it hadn't been shared in the first place". Sure, we could go for something like "if both CLONE_NEWNS *and* one of the things that might end up failing after copy_mnt_ns() call in create_new_namespaces() are set, force allocation of new fs_struct", but let's keep it simple - the cost of copy_fs_struct() is trivial. Another benefit is that copy_mnt_ns() with CLONE_NEWNS *always* gets a freshly allocated fs_struct, yet to be attached to anything. That seriously simplifies the analysis... FWIW, that bug had been there since the introduction of unshare(2) ;-/
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
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unshare组件中unshare_fs函数在CLONE_NEWNS和CLONE_NEWCGROUP组合时处理不当，可能导致挂载树状态不一致。
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 741a295130606143edbf9fc740f633dbc1e6225f ~ 845bf3c6963a52096d0d3866e4a92db77a0c03d8 -
Linux Linux 2.6.16 -

II. Public POCs for CVE-2026-43472

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III. Intelligence Information for CVE-2026-43472

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Patches & Fixes for CVE-2026-43472 (8)

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-2026-43379 9.8 CRITICAL ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
CVE-2026-43414 9.8 CRITICAL scsi: qla2xxx: Completely fix fcport double free
CVE-2026-43304 9.8 CRITICAL libceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-43465 9.8 CRITICAL net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-43384 9.8 CRITICAL net/tcp-ao: Fix MAC comparison to be constant-time
CVE-2026-43402 9.8 CRITICAL kthread: consolidate kthread exit paths to prevent use-after-free
CVE-2026-43383 9.4 CRITICAL net/tcp-md5: Fix MAC comparison to be constant-time
CVE-2026-43406 9.1 CRITICAL libceph: prevent potential out-of-bounds reads in process_message_header()
CVE-2026-43407 9.1 CRITICAL libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
CVE-2026-43284 8.8 HIGH xfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-43322 8.8 HIGH Bluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-43391 8.8 HIGH nsfs: tighten permission checks for handle opening
CVE-2026-43291 8.3 HIGH net: nfc: nci: Fix parameter validation for packet data
CVE-2026-43466 8.2 HIGH net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery
CVE-2026-43365 8.2 HIGH xfs: fix undersized l_iclog_roundoff values

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-2026-43472

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