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CVE-2026-53271— ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers

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基金会开源的操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于为对opinfo->conn进行空指针检查，可能导致攻击者触发空指针取消引用。

AI Predicted 7.5 Difficulty: Moderate EPSS 0.11% · P1

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 13

VendorProduct Version RangeStatus
Linux Linux 8df4bcdb0a4232192b2445256c39b787d58ef14d< 945a86b21b40fb17183f5b27461baa6f03e2467f affected
c8efcc786146a951091588e5fa7e3c754850cb3c< 1ff58dcfcab434ebb51649da33774fbb8e1f7b67 affected
c8efcc786146a951091588e5fa7e3c754850cb3c< e735dbd489e3ea02be78dba991056fe1138be51e affected
c8efcc786146a951091588e5fa7e3c754850cb3c< 75e33deda658c1ab3a9336cbdb1436536f9b3660 affected
c8efcc786146a951091588e5fa7e3c754850cb3c< b003086d76968298f22e7cf62239833b5a3a06b1 affected
6.6.32< 6.6.143 affected
6.9 affected
< 6.9 unaffected
… +5 more rows
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I. Basic Information for CVE-2026-53271

Vulnerability Information
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Vulnerability Title
ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 -- a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown.
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基金会开源的操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于为对opinfo->conn进行空指针检查，可能导致攻击者触发空指针取消引用。
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 8df4bcdb0a4232192b2445256c39b787d58ef14d ~ 945a86b21b40fb17183f5b27461baa6f03e2467f -
Linux Linux 6.9 -

II. Public POCs for CVE-2026-53271

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III. Intelligence Information for CVE-2026-53271

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Patches & Fixes for CVE-2026-53271 (4)

Same Patch Batch · Linux · 2026-06-25 · 146 CVEs total

CVE-2026-53176 9.8 CRITICAL IB/isert: Reject login PDUs shorter than ISER_HEADERS_LEN
CVE-2026-53228 9.8 CRITICAL ipv6: sit: reload inner IPv6 header after GSO offloads
CVE-2026-53151 9.8 CRITICAL rxrpc: Fix the ACK parser to extract the SACK table for parsing
CVE-2026-53221 9.8 CRITICAL ip6_vti: fix incorrect tunnel matching in vti6_tnl_lookup()
CVE-2026-53247 9.8 CRITICAL net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown
CVE-2026-53216 9.8 CRITICAL net: mvpp2: limit XDP frame size to the RX buffer
CVE-2026-53260 9.8 CRITICAL tcp: Add preempt_{disable,enable}_nested() in reqsk_queue_hash_req().
CVE-2026-53246 9.8 CRITICAL sctp: validate cached peer INIT chunk length in COOKIE_ECHO processing
CVE-2026-53175 9.8 CRITICAL inet: frags: fix use-after-free caused by the fqdir_pre_exit() flush
CVE-2026-53215 9.8 CRITICAL net: mvpp2: refill RX buffers before XDP or skb use
CVE-2026-53131 9.4 CRITICAL netfilter: require Ethernet MAC header before using eth_hdr()
CVE-2026-53225 9.1 CRITICAL sctp: fix uninit-value in __sctp_rcv_asconf_lookup()
CVE-2026-53224 9.1 CRITICAL sctp: validate embedded INIT chunk and address list lengths in cookie
CVE-2026-53186 9.1 CRITICAL RDMA/srp: bound SRP_RSP sense copy by the received length
CVE-2026-53240 8.8 HIGH xfrm: iptfs: fix use-after-free on first_skb in __input_process_payload
CVE-2026-53171 8.8 HIGH accel/ethosu: fix arithmetic issues in dma_length()
CVE-2026-53232 8.8 HIGH net: phy: clean the sfp upstream if phy probing fails
CVE-2026-53159 8.8 HIGH misc: fastrpc: fix DMA address corruption due to find_vma misuse
CVE-2026-53170 8.8 HIGH accel/ethosu: reject DMA commands with uninitialized length
CVE-2026-53188 8.8 HIGH RDMA/core: Validate the passed in fops for ib_get_ucaps()

Showing top 20 of 146 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-53271

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