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CVE-2026-43376— ksmbd: fix use-after-free by using call_rcu() for oplock_info

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ksmbd在opinfo_get和proc_show_files等RCU读侧临界区中立即释放oplock_info，导致释放后重用。

CVSS 9.8 · Critical EPSS 0.65% · P50

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux 296cb5457cc6f4a754c4ae29855f8a253d52bcc6< 302fef75512b2c8329a3f5efab1ae7ba2562387a affected
d54ab1520d43e95f9b2e22d7a05fc9614192e5a5< 08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c affected
18b4fac5ef17f77fed9417d22210ceafd6525fc7< 1d6abf145615dbfe267ce3b0a271f95e3780e18e affected
18b4fac5ef17f77fed9417d22210ceafd6525fc7< ce8507ee82c888126d8e7565e27c016308d24cde affected
18b4fac5ef17f77fed9417d22210ceafd6525fc7< 1dfd062caa165ec9d7ee0823087930f3ab8a6294 affected
d73686367ad68534257cd88a36ca3c52cb8b81d8 affected
6.6.88< 6.6.130 affected
6.12.25< 6.12.78 affected
… +8 more rows
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I. Basic Information for CVE-2026-43376

Vulnerability Information
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Vulnerability Title
ksmbd: fix use-after-free by using call_rcu() for oplock_info
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free by using call_rcu() for oplock_info ksmbd currently frees oplock_info immediately using kfree(), even though it is accessed under RCU read-side critical sections in places like opinfo_get() and proc_show_files(). Since there is no RCU grace period delay between nullifying the pointer and freeing the memory, a reader can still access oplock_info structure after it has been freed. This can leads to a use-after-free especially in opinfo_get() where atomic_inc_not_zero() is called on already freed memory. Fix this by switching to deferred freeing using call_rcu().
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/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
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ksmbd在opinfo_get和proc_show_files等RCU读侧临界区中立即释放oplock_info，导致释放后重用。
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 296cb5457cc6f4a754c4ae29855f8a253d52bcc6 ~ 302fef75512b2c8329a3f5efab1ae7ba2562387a -
Linux Linux 6.15 -

II. Public POCs for CVE-2026-43376

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III. Intelligence Information for CVE-2026-43376

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Patches & Fixes for CVE-2026-43376 (5)

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

CVE-2026-43378 9.8 CRITICAL smb: server: fix use-after-free in smb2_open()
CVE-2026-43341 9.8 CRITICAL net/ipv6: ioam6: prevent schema length wraparound in trace fill
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-2026-43402 9.8 CRITICAL kthread: consolidate kthread exit paths to prevent use-after-free
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-2026-43391 8.8 HIGH nsfs: tighten permission checks for handle opening
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
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-2026-43376

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