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CVE-2026-31444— ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()

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smb_grant_oplock函数存在释放后重用和空指针取消引用，可能导致并发读取时访问已释放节点或空指针。

CVSS 9.8 · Critical EPSS 0.45% · P38

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 9

VendorProduct Version RangeStatus
Linux Linux 302fef75512b2c8329a3f5efab1ae7ba2562387a< 9e785f004cbc56390479b77375726ea9b0d1a8a6 affected
08aa9f3c8cf4d0bee44df540dfe34e8d64069f2c< 7de55bba69cbf0f9280daaea385daf08bc076121 affected
1d6abf145615dbfe267ce3b0a271f95e3780e18e< a5c6f6d6ceefed2d5210ee420fb75f8362461f46 affected
ce8507ee82c888126d8e7565e27c016308d24cde< 6d7e5a918c1d0aad06db0e17677b66fc9a471021 affected
1dfd062caa165ec9d7ee0823087930f3ab8a6294< 48623ec358c1c600fa1e38368746f933e0f1a617 affected
6.6.130< 6.6.131 affected
6.12.78< 6.12.80 affected
6.18.19< 6.18.21 affected
… +1 more rows
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I. Basic Information for CVE-2026-31444

Vulnerability Information
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Vulnerability Title
ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free and NULL deref in smb_grant_oplock() smb_grant_oplock() has two issues in the oplock publication sequence: 1) opinfo is linked into ci->m_op_list (via opinfo_add) before add_lease_global_list() is called. If add_lease_global_list() fails (kmalloc returns NULL), the error path frees the opinfo via __free_opinfo() while it is still linked in ci->m_op_list. Concurrent m_op_list readers (opinfo_get_list, or direct iteration in smb_break_all_levII_oplock) dereference the freed node. 2) opinfo->o_fp is assigned after add_lease_global_list() publishes the opinfo on the global lease list. A concurrent find_same_lease_key() can walk the lease list and dereference opinfo->o_fp->f_ci while o_fp is still NULL. Fix by restructuring the publication sequence to eliminate post-publish failure: - Set opinfo->o_fp before any list publication (fixes NULL deref). - Preallocate lease_table via alloc_lease_table() before opinfo_add() so add_lease_global_list() becomes infallible after publication. - Keep the original m_op_list publication order (opinfo_add before lease list) so concurrent opens via same_client_has_lease() and opinfo_get_list() still see the in-flight grant. - Use opinfo_put() instead of __free_opinfo() on err_out so that the RCU-deferred free path is used. This also requires splitting add_lease_global_list() to take a preallocated lease_table and changing its return type from int to void, since it can no longer fail.
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smb_grant_oplock函数存在释放后重用和空指针取消引用，可能导致并发读取时访问已释放节点或空指针。
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)

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Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 302fef75512b2c8329a3f5efab1ae7ba2562387a ~ 9e785f004cbc56390479b77375726ea9b0d1a8a6 -
Linux Linux 6.6.130 ~ 6.6.131 -

II. Public POCs for CVE-2026-31444

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III. Intelligence Information for CVE-2026-31444

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-31463 9.8 CRITICAL iomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-31436 9.8 CRITICAL dmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-31478 9.8 CRITICAL ksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
CVE-2026-31501 9.8 CRITICAL net: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-31448 9.4 CRITICAL ext4: avoid infinite loops caused by residual data
CVE-2026-31432 8.8 HIGH ksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-31433 8.8 HIGH ksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-31435 8.8 HIGH netfs: Fix read abandonment during retry
CVE-2026-31450 8.8 HIGH ext4: publish jinode after initialization
CVE-2026-31476 8.2 HIGH ksmbd: do not expire session on binding failure
CVE-2026-31464 8.1 HIGH scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-31513 8.1 HIGH Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-31488 7.8 HIGH drm/amd/display: Do not skip unrelated mode changes in DSC validation
CVE-2026-31453 7.8 HIGH xfs: avoid dereferencing log items after push callbacks
CVE-2026-31490 7.8 HIGH drm/xe/pf: Fix use-after-free in migration restore
CVE-2026-31494 7.8 HIGH net: macb: use the current queue number for stats
CVE-2026-31502 7.8 HIGH team: fix header_ops type confusion with non-Ethernet ports
CVE-2026-31449 7.8 HIGH ext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-31504 7.8 HIGH net: fix fanout UAF in packet_release() via NETDEV_UP race
CVE-2026-31505 7.8 HIGH iavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

Showing top 20 of 100 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31444

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