Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-31709— smb: client: validate the whole DACL before rewriting it in cifsacl

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build_sec_desc()和id_mode_to_cifs_acl()中DACL验证不完整，可能导致恶意服务器返回截断的DACL驱动ACE遍历超出验证范围。

CVSS 8.8 · High EPSS 0.26% · P16

Possible ATT&CK Techniques 1 AI

T1211 · Exploitation for Stealth

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< b8603d9ae6c9087662b098619996bc4a8064319d affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< c2abdebf72000a64603ced84d36ccbd164f11391 affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< 8e47d297e7cf9a6029a0d38e7b22faba7d7aaf12 affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< d92f3f0b22414e7515696a02224d0af55e3004a3 affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< ff0ca46b13b9ef6edbcd238a3b6caacfef8ba0e5 affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< b78db9bddc84136f6a0bb49e8883cf200dfb87a8 affected
bc3e9dd9d104ca1b75644eab87b38ce8a924aef4< 0a8cf165566ba55a39fd0f4de172119dd646d39a affected
5.12 affected
… +8 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-31709

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
smb: client: validate the whole DACL before rewriting it in cifsacl
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: smb: client: validate the whole DACL before rewriting it in cifsacl build_sec_desc() and id_mode_to_cifs_acl() derive a DACL pointer from a server-supplied dacloffset and then use the incoming ACL to rebuild the chmod/chown security descriptor. The original fix only checked that the struct smb_acl header fits before reading dacl_ptr->size or dacl_ptr->num_aces. That avoids the immediate header-field OOB read, but the rewrite helpers still walk ACEs based on pdacl->num_aces with no structural validation of the incoming DACL body. A malicious server can return a truncated DACL that still contains a header, claims one or more ACEs, and then drive replace_sids_and_copy_aces() or set_chmod_dacl() past the validated extent while they compare or copy attacker-controlled ACEs. Factor the DACL structural checks into validate_dacl(), extend them to validate each ACE against the DACL bounds, and use the shared validator before the chmod/chown rebuild paths. parse_dacl() reuses the same validator so the read-side parser and write-side rewrite paths agree on what constitutes a well-formed incoming DACL.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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build_sec_desc()和id_mode_to_cifs_acl()中DACL验证不完整，可能导致恶意服务器返回截断的DACL驱动ACE遍历超出验证范围。
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 bc3e9dd9d104ca1b75644eab87b38ce8a924aef4 ~ b8603d9ae6c9087662b098619996bc4a8064319d -
Linux Linux 5.12 -

II. Public POCs for CVE-2026-31709

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-31709

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-31709 (7)

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

CVE-2026-43037 9.8 CRITICAL ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
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-2026-43011 9.8 CRITICAL net/x25: Fix potential double free of skb
CVE-2026-31705 9.8 CRITICAL ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
CVE-2026-31718 9.8 CRITICAL ksmbd: fix use-after-free in __ksmbd_close_fd() via durable scavenger
CVE-2026-43048 8.8 HIGH HID: core: Mitigate potential OOB by removing bogus memset()
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-2026-31773 8.8 HIGH Bluetooth: SMP: derive legacy responder STK authentication from MITM state
CVE-2026-31717 8.8 HIGH ksmbd: validate owner of durable handle on reconnect
CVE-2026-43018 8.8 HIGH Bluetooth: hci_event: fix potential UAF in hci_le_remote_conn_param_req_evt
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-2026-31779 8.1 HIGH wifi: iwlwifi: mvm: fix potential out-of-bounds read in iwl_mvm_nd_match_info_handler()
CVE-2026-31771 8.1 HIGH Bluetooth: hci_event: move wake reason storage into validated event handlers
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-2026-31772 7.8 HIGH Bluetooth: hci_sync: fix stack buffer overflow in hci_le_big_create_sync
CVE-2026-43019 7.8 HIGH Bluetooth: hci_conn: fix potential UAF in set_cig_params_sync

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-2026-31709

No comments yet

Leave a comment