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CVE-2026-31705— ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment

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smb2_get_ea()中EA对齐的memset()未检查剩余空间，可能导致在复合请求中写入超出缓冲区边界。

CVSS 9.8 · Critical EPSS 0.40% · P32

Affected Version Matrix 17

VendorProduct Version RangeStatus
Linux Linux 9f297df20d93411c0b4ddad7f88ba04a7cd36e77< ddbbc8b2a09dd2cfed90871313e3691ae1db08a2 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< ffbce350c6fd1e99116ea57383b9031717e36d3b affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 98f3de6ef4efbd899348d333f0902dc4ff14380c affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 790304c02bf9bd7b8171feda4294d6e62d32ae8f affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 922d48fe8c19f388ffa2f709f33acaae4e408de2 affected
e2b76ab8b5c9327ab2dae6da05d0752eb2f4771d< 30010c952077a1c89ecdd71fc4d574c75a8f5617 affected
f2283680a80571ca82d710bc6ecd8f8beac67d63 affected
6.1.71< 6.1.175 affected
… +9 more rows
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I. Basic Information for CVE-2026-31705

Vulnerability Information
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Vulnerability Title
ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds write in smb2_get_ea() EA alignment smb2_get_ea() applies 4-byte alignment padding via memset() after writing each EA entry. The bounds check on buf_free_len is performed before the value memcpy, but the alignment memset fires unconditionally afterward with no check on remaining space. When the EA value exactly fills the remaining buffer (buf_free_len == 0 after value subtraction), the alignment memset writes 1-3 NUL bytes past the buf_free_len boundary. In compound requests where the response buffer is shared across commands, the first command (e.g., READ) can consume most of the buffer, leaving a tight remainder for the QUERY_INFO EA response. The alignment memset then overwrites past the physical kvmalloc allocation into adjacent kernel heap memory. Add a bounds check before the alignment memset to ensure buf_free_len can accommodate the padding bytes. This is the same bug pattern fixed by commit beef2634f81f ("ksmbd: fix potencial OOB in get_file_all_info() for compound requests") and commit fda9522ed6af ("ksmbd: fix OOB write in QUERY_INFO for compound requests"), both of which added bounds checks before unconditional writes in QUERY_INFO response handlers.
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smb2_get_ea()中EA对齐的memset()未检查剩余空间，可能导致在复合请求中写入超出缓冲区边界。
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 9f297df20d93411c0b4ddad7f88ba04a7cd36e77 ~ ddbbc8b2a09dd2cfed90871313e3691ae1db08a2 -
Linux Linux 6.6 -

II. Public POCs for CVE-2026-31705

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III. Intelligence Information for CVE-2026-31705

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Patches & Fixes for CVE-2026-31705 (6)

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-2026-31718 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-2026-31709 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-2026-31779 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-2026-31708 8.1 HIGH smb: client: fix OOB read in smb2_ioctl_query_info QUERY_INFO path
CVE-2026-43051 8.1 HIGH HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
CVE-2026-31769 7.8 HIGH gpib: fix use-after-free in IO ioctl handlers
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-2026-31705

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