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CVE-2026-31704— ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

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set_posix_acl_entries_dacl()和set_ntacl_dacl()中u16 DACL大小累加可能溢出，可能导致指针运算错误覆盖已写入的ACE。

AI Predicted 7.8 Difficulty: Moderate EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 41e53a773db6342ac9a689ee5ba635c31744c9f0 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 8d5729350b236896f51379588d9a690b7fafb8db affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< e1955a94b6f17f4b058afa955a6f187eb3ed7615 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 299f962c0b02d048fb45d248b4da493d03f3175d affected
5.15 affected
< 5.15 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-31704

Vulnerability Information
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Vulnerability Title
ksmbd: use check_add_overflow() to prevent u16 DACL size overflow
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char *)pndace + *size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.
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set_posix_acl_entries_dacl()和set_ntacl_dacl()中u16 DACL大小累加可能溢出，可能导致指针运算错误覆盖已写入的ACE。
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 ~ 41e53a773db6342ac9a689ee5ba635c31744c9f0 -
Linux Linux 5.15 -

II. Public POCs for CVE-2026-31704

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III. Intelligence Information for CVE-2026-31704

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Patches & Fixes for CVE-2026-31704 (6)

Same Patch Batch · Linux · 2026-05-01 · 146 CVEs total

CVE-2026-43011 9.8 CRITICAL net/x25: Fix potential double free of skb
CVE-2026-43037 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
CVE-2026-31705 9.8 CRITICAL ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
CVE-2026-43038 9.8 CRITICAL ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
CVE-2026-43039 9.8 CRITICAL net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch
CVE-2026-31718 9.8 CRITICAL ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
CVE-2026-43018 8.8 HIGH Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt
CVE-2026-31773 8.8 HIGH Bluetooth: SMP: derive legacy responder STK authentication from MITM state
CVE-2026-31739 8.8 HIGH crypto: tegra - Add missing CRYPTO_ALG_ASYNC
CVE-2026-31735 8.8 HIGH iommupt: Fix short gather if the unmap goes into a large mapping
CVE-2026-31717 8.8 HIGH ksmbd: validate owner of durable handle on reconnect
CVE-2026-43048 8.8 HIGH HID: core: Mitigate potential OOB by removing bogus memset()
CVE-2026-31709 8.8 HIGH smb: client: validate the whole DACL before rewriting it in cifsacl
CVE-2026-31706 8.8 HIGH ksmbd: validate num_aces and harden ACE walk in smb_inherit_dacl()
CVE-2026-31712 8.3 HIGH ksmbd: require minimum ACE size in smb_check_perm_dacl()
CVE-2026-31771 8.1 HIGH Bluetooth: hci_event: move wake reason storage into validated event handlers
CVE-2026-31779 8.1 HIGH wifi: iwlwifi: mvm: fix potential out-of-bounds read in iwl_mvm_nd_match_info_handler()
CVE-2026-43051 8.1 HIGH HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
CVE-2026-31708 8.1 HIGH smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
CVE-2026-31695 7.8 HIGH wifi: virt_wifi: remove SET_NETDEV_DEV to avoid use-after-free

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-2026-31704

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