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CVE-2026-31477— ksmbd: fix memory leaks and NULL deref in smb2_lock()

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，该漏洞源于错误处理不当和空指针解引用，可能导致内存泄露和内核崩溃。

CVSS 7.5 · High EPSS 0.68% · P52

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< cdac6f7e7e428dc70e3b5898ac6999a72ed13993 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 91aeaa7256006d79a37298f5a1df23325db91599 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 3cdacd11b41569ce75b3162142240f2355e04900 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< aab42f0795620cf0d3955a520f571f697d0f9a2a affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 309b44ed684496ed3f9c5715d10b899338623512 affected
5.15 affected
< 5.15 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-31477

Vulnerability Information
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Vulnerability Title
ksmbd: fix memory leaks and NULL deref in smb2_lock()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix memory leaks and NULL deref in smb2_lock() smb2_lock() has three error handling issues after list_del() detaches smb_lock from lock_list at no_check_cl: 1) If vfs_lock_file() returns an unexpected error in the non-UNLOCK path, goto out leaks smb_lock and its flock because the out: handler only iterates lock_list and rollback_list, neither of which contains the detached smb_lock. 2) If vfs_lock_file() returns -ENOENT in the UNLOCK path, goto out leaks smb_lock and flock for the same reason. The error code returned to the dispatcher is also stale. 3) In the rollback path, smb_flock_init() can return NULL on allocation failure. The result is dereferenced unconditionally, causing a kernel NULL pointer dereference. Add a NULL check to prevent the crash and clean up the bookkeeping; the VFS lock itself cannot be rolled back without the allocation and will be released at file or connection teardown. Fix cases 1 and 2 by hoisting the locks_free_lock()/kfree() to before the if(!rc) check in the UNLOCK branch so all exit paths share one free site, and by freeing smb_lock and flock before goto out in the non-UNLOCK branch. Propagate the correct error code in both cases. Fix case 3 by wrapping the VFS unlock in an if(rlock) guard and adding a NULL check for locks_free_lock(rlock) in the shared cleanup. Found via call-graph analysis using sqry.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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，该漏洞源于错误处理不当和空指针解引用，可能导致内存泄露和内核崩溃。
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 e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 ~ cdac6f7e7e428dc70e3b5898ac6999a72ed13993 -
Linux Linux 5.15 -

II. Public POCs for CVE-2026-31477

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III. Intelligence Information for CVE-2026-31477

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

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-2026-31463 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-2026-31444 9.8 CRITICAL ksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-31448 9.4 CRITICAL ext4: avoid infinite loops caused by residual data
CVE-2026-31450 8.8 HIGH ext4: publish jinode after initialization
CVE-2026-31435 8.8 HIGH netfs: Fix read abandonment during retry
CVE-2026-31433 8.8 HIGH ksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-31432 8.8 HIGH ksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-31476 8.2 HIGH ksmbd: do not expire session on binding failure
CVE-2026-31513 8.1 HIGH Bluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-31464 8.1 HIGH scsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-31449 7.8 HIGH ext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-31454 7.8 HIGH xfs: save ailp before dropping the AIL lock in push callbacks
CVE-2026-31453 7.8 HIGH xfs: avoid dereferencing log items after push callbacks
CVE-2026-31471 7.8 HIGH xfrm: iptfs: only publish mode_data after clone setup
CVE-2026-31502 7.8 HIGH team: fix header_ops type confusion with non-Ethernet ports
CVE-2026-31468 7.8 HIGH vfio/pci: Fix double free in dma-buf feature
CVE-2026-31494 7.8 HIGH net: macb: use the current queue number for 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-2026-31477

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