Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1 ksmbd smb2_get_ea out-of-bounds write

CVSS Meta Temp Score
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CTI Interest Score
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8.7$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1. It has been rated as critical. This vulnerability affects the function smb2_get_ea of the component ksmbd. The manipulation leads to out-of-bounds write. This vulnerability is referenced as CVE-2026-31705. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1. This issue affects the function smb2_get_ea of the component ksmbd. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. Using CWE to declare the problem leads to CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-31705 since 03/09/2026. The exploitation is known to be easy. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/05/2026).

The vulnerability scanner Nessus provides a plugin with the ID 325059 (Debian dla-4665 : affs-modules-6.1.0-48-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.136, 6.12.84, 6.18.25, 7.0.2 or 7.1-rc1 eliminates this vulnerability. Applying the patch ffbce350c6fd1e99116ea57383b9031717e36d3b/98f3de6ef4efbd899348d333f0902dc4ff14380c/790304c02bf9bd7b8171feda4294d6e62d32ae8f/922d48fe8c19f388ffa2f709f33acaae4e408de2/30010c952077a1c89ecdd71fc4d574c75a8f5617 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (325059) and CERT Bund (WID-SEC-2026-1346). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Microsoft Azure Linux
  • Red Hat OpenShift

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.9
VulDB Meta Temp Score: 8.7

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.8
CNA Vector (Linux): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds write
CWE: CWE-787 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 325059
Nessus Name: Debian dla-4665 : affs-modules-6.1.0-48-4kc-malta-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.136/6.12.84/6.18.25/7.0.2/7.1-rc1
Patch: ffbce350c6fd1e99116ea57383b9031717e36d3b/98f3de6ef4efbd899348d333f0902dc4ff14380c/790304c02bf9bd7b8171feda4294d6e62d32ae8f/922d48fe8c19f388ffa2f709f33acaae4e408de2/30010c952077a1c89ecdd71fc4d574c75a8f5617

Timelineinfo

03/09/2026 CVE reserved
05/01/2026 +52 days Advisory disclosed
05/01/2026 +0 days VulDB entry created
07/05/2026 +65 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31705 (🔒)
GCVE (CVE): GCVE-0-2026-31705
GCVE (VulDB): GCVE-100-360605
CERT Bund: WID-SEC-2026-1346 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/01/2026 16:50
Updated: 07/05/2026 20:06
Changes: 05/01/2026 16:50 (59), 05/04/2026 14:10 (7), 06/04/2026 05:24 (11), 06/09/2026 10:08 (1), 06/30/2026 19:56 (3), 07/05/2026 20:06 (2)
Complete: 🔍
Cache ID: 216::103

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